ACDE Apple Connect Device External? ACDEClient.framework, old two-step verification, derived from a company-internal AppleConnect system? server: appleconnect.apple.com
ACDE Apple Connect Device External? ACDEClient.framework, old two-step verification, derived from a company-internal AppleConnect system?
ACFS Apple Clustered File System; deprecated file system for Xsan; acfs.framework
Acoustic ID Siri feature to recognize songs
Activation cryptographic check-in with iCloud to lock devices reported by the user as lost; verified by iBoot; MobileActivationMacOS.framework; launchd service: com.apple.mobileactivationd; servers: humb.apple.com, albert.apple.com
Activity jobs, coarse-grained work units of applications; tracked by the system across XPC, bears a QoS class for scheduling; low-level mechanism not to be confused with User Activity
AE Apple Events; messaging system to invoke application functionality; CoreServices.framework/AE.framework; launchd services: com.apple.coreservices.appleevents, com.apple.AEServer (AE over network)
Aegir astronomy watch face and lock screen; /System/Library/CoreServices/AegirProxyApp.app
AGC Apple Graphics Control, management of multiple displays and display port connections; launchd service: com.apple.displaypolicyd
AHAP Apple Haptic Audio Pattern; file format for simultaneous audio and haptic data; CoreHaptics.framework
AIR Apple Intermediate Representation; synthetic bytecode architecture target for GPU binary toolchain
Alloy substrate for communication between user devices over Bluetooth and devices to iCloud, implemented over IDS; /System/Library/IdentityServices/ServiceDefinitions; launchd service: com.apple.identityservicesd
@@ -49,6 +51,7 @@ AVB Audio Video Bridging, low-latency audio over Ethernet; launchd service: com.
AWD Apple Wireless Diagnostics, sends system telemetry to Apple; CoreAnalytics.framework, WirelessDiagnostics.framework; launchd services: com.apple.awdd, com.apple.analyticsd
AWDL Apple Wireless Direct Link; secondary WiFi interface that runs in parallel to an active WiFi access point connection, similar to WiFi Direct (p2p interface), uses a randomized MAC, used for peer-to-peer networking: AirDrop, AirPlay; DeviceToDeviceManager.framework
Bezel on-screen overlays for hardware volume buttons, screen brightness, Bluetooth HID, and others; /Library/Application Support/Apple/BezelServices, launchd services: com.apple.loginwindow, com.apple.OSDUIHelper
Blast Door sandboxed sanitization process for untrusted iMessage input; BlastDoor.framework
BOM Bill of Materials; format to store contents of installer Packages; command line tool: lsbom
@@ -64,9 +67,11 @@ CAML Core Animation Markup Language; XML file format for layers, shapes and anim
Carousel derivative of SpringBoard for Watch home screen, watch face, and notification center
Celestial media streaming used by ReplayKit for game broadcasts; Celestial.framework
Certificates validity checked using CRLs, OCSP stapling, and transparency logs; /System/Library/Security/Certificates.bundle; launchd services: com.apple.trustd, com.apple.trustd.agent, com.apple.ocspd; command line tool: crlrefresh
CHIP Connected Home over IP; Matter; integrated into HomeKit; CHIP.framework
Chamois Stage Manager
CHIP Connected Home over IP; Matter; integrated into HomeKit; CHIPPlugin.framework
Circle cryptographic primitive to exchange public keys of trusted devices of a user, signed by Circle peers; iCloud identity added as additional Circle peer, private key synced across all trusted devices, new devices can pull this key from Secure Backup to join the Circle; per-device Circles stored in CKKS for two-factor accounts (Octagon); KeychainCircle.framework; command line tools: tpctl, otctl (Octagon)
CKKS CloudKit Key Sync, end-to-end secure syncing for credentials, seeded by Circle; currently includes ApplePay, AutoUnlock, CreditCards, DevicePairing, Engram, Health, Home, Manatee, SOS, WiFi and other keys; launchd service: com.apple.secd; command line tool: ckksctl
Clarity customizable accessibility mode for simplified UI; ClarityFoundation.framework
Classroom school teachers can create assignments for student iPads and track progress in Schoolwork app; ClassKit.framework; launchd service: com.apple.studentd
Cloud Pairing part of Alloy, Bluetooth out-of-band pairing over iCloud for Continuity; launchd service: com.apple.BTServer.cloudpairing (cloudpaird)
CMAS Commerial Mobile Alert System, now known as Wireless Emergency Alerts (WEA)
@@ -77,6 +82,8 @@ Continuity umbrella term for Handoff, Sidecar, SMS relay, Universal Clipboard, W
Control Center icons in menu/status bar and Bento Box controls UI, gradually replaces SystemUIServer on macOS; handles incoming AirPlay content; launchd services: com.apple.controlcenter, com.apple.SystemUIServer.agent
Cryptex Cryptographically sealed Extension of SSV, mount-invisible extension of the root volume, allows lightweight updates as part of Rapid Security Response; /System/Cryptexes (mountpoint), /System/Volumes/Preboot/*/cryptex1/current/*.dmg (disk images)
CSR Configurable Security Restrictions; XNU subsystem that is the basis for SIP
CTK Crypto Token Kit; smart card management, also for the Secure Element on iOS? launchd service: com.apple.ctkd; command line tool: sc_auth
CTS Centralized Task Scheduling; execution of DAS tasks; /System/Library/UserEventPlugins/com.apple.cts.plugin
CVMS Core VM Server/Service? compilation of GPU shaders; launchd service: com.apple.cvmsServ
@@ -89,21 +96,22 @@ Data Vault directories with the UF_DATAVAULT special flag; CSR limits access to
DAV Distributed Authoring and Versioning; network protocol on top of HTTP for syncing calendars (CalDAV), contacts (CardDAV), and formerly also bookmarks (BookmarkDAV)
DCP Display Co-Processor
DEP Device Enrollment Program; devices check in with Apple during Setup Assistant to query for their enrollment status, retrieve MDM server URL to fetch initial configuration profile
Developer Mode enables launching of self-compiled apps in iOS, rough equivalent to System Policy; command line tool: devmodectl
DFR Dynamic Function Row?, TouchBar; /System/Library/CoreServices/ControlStrip.app; DFRFoundation.framework
DFU Device Firmware Update; special boot mode where iOS has not booted and the system can be installed over the Lightning connection
Differential Privacy crowdsourcing without user tracking; privacy budget for management of anonymity set; used for keyboard words, emoji, Spotlight searches, Parsec deep links, HealthKit usage, Safari telemetry; /System/Library/DifferentialPrivacy; stored in /var/db/DifferentialPrivacy; launchd service: com.apple.dprivacyd
Digital Separation safety check feature to inhibit sharing relationships; DigitalSeparation.framework
DND Do Not Disturb
DSID Destination Signaling Identifier, unique ID for IDS login on a specific device
Duet telemetry collection engine for system and user events, forecasting by machine learning, backend for DAS, Proactive, Relevance, Screen Time, thermal and battery management; /System/Library/DuetKnowledgeBase; CoreDuet.framework, CoreKnowledge.framework, CorePrediction.framework; launchd services: com.apple.coreduetd, com.apple.knowledge-agent
Dyld Shared Cache dynamic linker cache, stores all system libraries in prelinked form, original library files are removed; /System/Library/dyld; command line tool: update_dyld_shared_cache
Dyld Shared Cache dynamic linker cache, stores all system libraries in prelinked form, original library files are removed; /System/Volumes/Preboot/Cryptexes/OS/System/Library/dyld; command line tools: dyld_info, dyld_usage, update_dyld_shared_cache
EAS Exchange Active Sync; network protocol for accessing Microsoft Exchange servers
EDR Extended Dynamic Range; rendering with transfer function extending beyond sRGB white; implemented natively on XDR displays and by backlight modulation on others; HDRProcessing.framework
Energy Impact unitless metric for per-application energy consumption, machine-specific coefficients; /usr/share/pmenergy, /usr/share/kpep; launchd services: com.apple.sysmond, com.apple.thermald; command line tool: powermetrics
Engram Messages in iCloud; devices store received iMessages in CloudKit; Engram.framework
Entitlements capability-like attributes bound to executables by code signing; some entitlements like App Sandbox restrict ambient authority, some gradually relieve those restrictions (using Seatbelt), some services or system calls grant privilege based on caller entitlements
ESS IDS user directory, public key distribution for iMessage and CloudKit sharing, uses Transparency; server: *.ess.apple.com; launchd service: com.apple.identityservicesd
Event Monitor simple rules engine for running commands on various systen events; apparently not used by default; /etc/emond.d, /var/db/emondClients; launchd service: com.apple.emond
FaceTime video calls, employs the ICE (establishing peer-to-peer connection), STUN (session credential exchange) and SRTP (encrypted media streaming) protocols; FTServices.framework; launchd services: com.apple.videoconference.camera (avconferenced)
FairPlay DRM system used by app and media stores; CoreADI.framework, CoreFP.framework, CoreLSKD.framework; launchd services: com.apple.adid, com.apple.fairplayd (invoked by kernel through host special port 17), com.apple.lskdd; credentials stored in /var/db/fpsd
Family Circle Family Sharing; launchd services: com.apple.familycircled, com.apple.askpermissiond
@@ -114,7 +122,7 @@ FiDES Fi? Distributed Evaluation Service? aggregates Differential Privacy data f
File Provider infrastructure and extension system for syncing with cloud providers; placeholder files based on SF_DATALESS attribute in APFS; FileProvider.framework; locally stored in ~/Library/CloudStorage; command line tool: fileproviderctl
Find My … location sharing by explicitly querying devices remotely or collateral beacon detection using Search Party; FMCore.framework, FMF.framework; launchd service: com.apple.icloud.fmfd (find my friends)
Firmlink bi-directional non-symbolic link between the read-only system volume and the data volume, additional symlinks and mountpoints in the root directory are virtually allocated; /usr/share/firmlinks, /etc/synthetic.conf
Focus restriction modes for notification presentation; Focus.framework, DoNotDisturb.framework; local settings in ~/Library/DoNotDisturb
Focus restriction modes for notification presentation; focus filters for in-app display restrictions, communicat by Intents; Focus.framework, DoNotDisturb.framework; local settings in ~/Library/DoNotDisturb
FollowUp user interaction for Secure Backup wrapping with device passcode, CoreFollowUp.framework; launchd service: com.apple.followupd
FoundationDB fundamental iCloud storage database, marketed as CloudKit, separated into containers; records, blobs, and large asset storage with MMCS, server-side continuous queries can trigger push notifications, user management by IDS, sharing between users; PCS keys used for hierarchical zone, record, and asset encryption; CloudKitDaemon.framework; launchd service: com.apple.cloudd; locally stored in ~/Library/Caches/CloudKit, ~/Library/Containers/*/Data/CloudKit; command line tool: cktool
FPR Fast Permission Restrictions; Apple CPU registers to downgrade (old APRRs do bitmasking) or remap (SPRRs since M1) actual permissions of memory pages (the CTRR region) per thread; used for JIT protection and by AMFI to freeze user code after checking
@@ -130,7 +138,7 @@ HDI Hard Disk Image; command line tool: hdiutil
HeadBoard derivative of SpringBoard for tvOS home screen; /Applications/HeadBoard.app, /Applications/PineBoard.app
HLS HTTP Live Streaming
HSA Hardware Security Architecture; version 1 used for two-step verification, SOS with iCSC; version 2 for two-factor authentication, CKKS and Secure Backup with iCDP
HSM Hardware Security Module; HSM fleet runs escrow service for Secure Backup; public keys for authenticating the HSM services in /System/Library/Security/Certificates.bundle/Contents/Resources/AppleESCertificates.plist
HSM Hardware Security Module; HSM fleet runs escrow service for Secure Backup
iBoot boot loader stage after boot ROM or UEFI (macOS on Intel); intermediate Low-Level Bootloader (LLB); DFU mode is implemented here; /System/Library/CoreServices/boot.efi
@@ -142,14 +150,14 @@ IDS Identity Service, also IDMS, Apple ID identity management for all of Apple
IDV Identity Verification? Touch ID and Face ID; /System/Library/AccessibilityBundles/CoreIDVUI.axbundle
IM Instant Messaging; usually means iMessage and FaceTime
IMG4 boot files (Mach-O binaries or configuration data) with ASN.1 signature, contains RemotePolicy certificate constraints to restrict Boot Policy evaluation
Intent use-case-driven interaction with 3rd-party apps from a host app; used for Siri, Maps, Widgets (configuration); extension points: com.apple.intents-service, com.apple.intents-ui-service
Intent use-case-driven interaction with 3rd-party apps from a host app; used for Siri, Maps, Shortcuts, Widgets (configuration); definition file or programmatically using AppIntents.framework; command line tool: appintentsmetadataprocessor (Xcode extracts Intent definition at compile time); extension points: com.apple.intents-service, com.apple.intents-ui-service
IOKit device driver subsystem for in-kernel and DriverKit drivers, command line tool: ioreg
Ironwood dictation, customized on server with selected user data (contacts, app names, music titles, HomeKit names, Siri Shortcut phrases), not tied to Apple ID; SpeechRecognitionCore.framework; server: guzzoni.apple.com
ISP Image Signal Processor; camera imaging circuit in iPhones
ITML iTunes Markup Language; metdata tagging for media services; ITMLKit.framework
ITP Intelligent Tracking Prevention, cross-site tracking defenses in Safari, statistics and user interaction classify sites, cookies are partitioned and access is restricted
JARVIS Just A Rather Very Intelligent Scheduler, Mesos cluster manager for Siri, iCloud, AMS
Jellyfish Animoji
Jellyfish Animoji; /Applications/Jellyfish.app
Jetsam reclaiming of purgeable memory and termination of apps during memory pressure
JSC JavaScript Core; JavaScriptCore.framework; command line tool: jsc
Kalamata codename for the transition from x86 to ARM-based Apple Silicon
@@ -160,6 +168,7 @@ Keybag storage of protection class keys for Keychain and filesystem, protected b
Keychain storage for credentials; launchd service: com.apple.securityd; command line tools: certtool, security, systemkeychain
KIP Kernel Integrity Protection, locking of physical memory pages to prevent changes to kernel
Launch Services management for application launches, association of UTIs to apps, uses Spotlight to update cached info; launchd services: com.apple.coreservices.launchservicesd, com.apple.lsd; CoreServices.framework/LaunchServices.framework; command line tools: lsappinfo, lsregister
Live Files user mode filesystems, currently FAT, ExFAT, NTFS on external storage; UserFS.framework, UVFSXPCService.framework; launchd service: com.apple.filesystems.userfsd
Liverpool PCS codename for CloudKit
LKDC Local Key Distribution Center, Kerberos on client machines
LSM Latent Semantic Mapping, text analysis, used for spam filtering, command line tool: lsm
@@ -168,6 +177,7 @@ MAC Policy Mandatory Access Control subsystem in XNU, based on TrustedBSD, imple
Machine Learning Vision.framework, Espresso.framework, Futhark.framework, PhotoAnalysis.framework; used for Live Text and Visual Lookup; launchd service: com.apple.mediaanalysisd
Madrid iMessage; /System/Library/Messages
Manatee PCS key for some CloudKit containers are synced via CKKS, so data is unreadable to Apple (credential management codenames: Plesio, Stingray, Cuttlefish)
Mandrake emergency siren on Apple Watch Ultra; /Applications/Mandrake.app
Mangrove transfering UI tiles over XPC; Mangrove.framework, IOSurface.framework
Marco Marco.framework, something about IDS and communication (iMessage, Calls), logging?
Marklar codename from the PowerPC era for the port to x86, served the transition to Intel CPUs
@@ -194,7 +204,7 @@ Notarization app security scan by Apple; cryptographic proof stapled to code sig
Noticeboard User Notifications for Software Update and App Store, Noticeboard.framework; launchd services: com.apple.noticeboard.state (nbstated), com.apple.noticeboard.agent (nbagent)
Notifications system notification bus, unrelated to the local/remote push notifications; launchd service: com.apple.notifyd, com.apple.kuncd (invoked by kernel through host special port 10); command line tool: notifyutil; complemented by framework-level notification system (CFNotification, NSNotification); launchd services: com.apple.distnoted.xpc.daemon, com.apple.distnoted.xpc.agent
NSP Network Service Proxy; per-app VPN and proxy settings, implements Private Relay; launchd service: com.apple.networkserviceproxy
OAH Rosetta; /usr/libexec/rosetta
OAH Rosetta; ahead-of-time compiler for Intel code on Apple Silicon; /usr/libexec/rosetta
ODR On-Demand Resources; loaded from App Store; launchd service: com.apple.appstored
Onboarding data protection splash screen shown by service-connected apps; /System/Library/OnBoardingBundles; OnBoardingKit.framework
Open Directory directory service for user, group, and machine management; plugin-based to use different backend stores (LDAP, Active Directory), local accounts in /private/var/db/dslocal; launchd service: com.apple.opendirectoryd; command line tools: dscacheutil, dscl, dsconfigad, dsconfigldap, dseditgroup, dsenableroot, dserr, dsexport, dsimport, dsmemberutil, odutil
@@ -203,6 +213,7 @@ OSA Open Scripting Architecture; scripting of applications from different fonten
OTUT One-Time Unlock Token; security mechanism to allow keybag unwrapping after updates
PAC Pointer Authentication Codes; pointers signed in unused bits to prevent ROP attacks
Packages unit of software installation; command line tools: pkgutil, installer, softwareupdate; launchd services: com.apple.softwareupdated, com.apple.bootinstalld, com.apple.installd, com.apple.system_installd, com.apple.uninstalld; /var/db/softwareupdate, /Library/Apple/System/Library/Receipts (system), /System/Library/Receipts (read-only), /private/var/db/receipts (App Store)
Packet Filter network traffic filtering subsystem from OpenBSD; command line tool: pfctl
Parsec Spotlight web results and searching of crowdsourced User Activity deep links; server: *.smoot.apple.com; launchd services: com.apple.parsecd, com.apple.parsec-fbf (Feedback Flush to Differential Privacy)
Password Breach monitoring of Keychain passwords against a breach database; round-robin matching in fixed-size batches, local match against common leaks, remote match using hash prefix; launchd service: com.apple.Safari.passwordbreachd
Pasteboard storage for cut, copy, and paste; type of content remembered as UTI; launchd service: com.apple.pboard; command line tools: pbcopy, pbpaste
@@ -216,6 +227,7 @@ PHASE Physical Audio Spatialization Engine; 3D sound rendering engine; Apple dev
Piano Mover Mail Drop; bulk mail attachments transfered over PCS; not to be confused with storage for iMessage attachments, which uses a CloudKit container
Plugin Extensions, XPC services bundled with apps or frameworks, discovery by Launch Services; launchd service: com.apple.pluginkit.pkd; command line tool: pluginkit
PMP Port Mapping Protocol; Apple alternative to UPnP, Bonjour service: _acp-sync._tcp
PowerUI battery management like smart charge and power save, learns from Duet and other data; PowerUI.framework; /var/db/PowerUI; launchd service: com.apple.PowerUIAgent
Preferences storage for user-configurable settings; launchd services: com.apple.cfprefsd.xpc.daemon, com.apple.cfprefsd.xpc.agent; stored in Library/Preferences, command line tool: defaults; interaction with Synced Defaults per /System/Library/DefaultsConfigurations
Private Relay two-hop onion routing with one entry and one exit node; Apple operates entry, third-party services operate exit nodes; QUIC for payload, ODoH for DNS, approximate IP geolocation via Waldo; authentication via Attestation, propagated to proxys using RSA blind signatures
@@ -244,13 +256,15 @@ Search Party portion of Find My service for offline devices; devices emit public
Seatbelt process sandbox by filtering system calls; profiles written in SBPL; /System/Library/Sandbox/Profiles, /usr/share/sandbox; default file access policy asks for TCC confirmation before access to folders with user data (like Documents) is allowed; command line tool: sandbox-exec; launchd service: com.apple.sandboxd (invoked by kernel through host special port 14 for logging)
Secure Backup escrow part of CKKS; escrow key individually wrapped with passcodes of trusted devices, stored in HSM to prevent brute forcing, uses SRP so passcodes are not visible to iCloud, limited number of recovery attempts; protocol called Lakitu, uses FollowUp; launchd service: com.apple.SecureBackupDaemon (com.apple.sbd); CloudServices.framework
SEP Secure Enclave Processor; dedicated ARM core for security services, runs L4/Darbat-based sepOS, inline encryption to DRAM, manages AES keys in storage DMA engine, factory-paired channels to Touch ID/Face ID hardware, Secure Element, Neural Engine; SEP can use but not read UID and GID keys; credential verification performed by hardware lockbox with retry count enforcement
Sequoia translation; downloadable language models can run on-device; /Applications/SequoiaTranslator.app, Translation.framework
Seymour Apple Fitness+; workout videos integrated with Watch sensors; SeymourCore.framework
SF Symbols scalable UI symbols; rendered with various color treatments; SFSymbols.framework
Sharing umbrella term for wireless proximity services: AirDrop, Continuity, Instant Hotspot, WiFi sharing; used by loginwindow for Watch unlock; Sharing.framework; launchd service: com.apple.sharingd; also serves connection sharing and remote disk
Shazam music recognition service; ShazamKit.framework; launchd service: com.apple.shazamd
Sidecar using iPhone/iPad as Mac accessory: camera for photos and scanning, annotations, external display over low-latency WiFi (llw interface) using avconferenced encoding; SidecarCore.framework; launchd services: com.apple.sidecar-display-agent (SidecarDisplayAgent), com.apple.sidecar-relay (SidecarRelay)
Sidecar using iPhone/iPad as Mac accessory: external camera and microphone (ContinuityCapture), camera for photos and scanning (DocumentCamera.framework), external display over low-latency WiFi (llw interface) using avconferenced encoding; SidecarCore.framework; launchd services: com.apple.sidecar-display-agent (SidecarDisplayAgent), com.apple.sidecar-relay (SidecarRelay)
Signpost telemetry API to report points of interest in code; launchd service: com.apple.signpost.signpost_reporter
Simulator running an iOS/tvOS/watchOS personality on macOS, uses sandboxing and a separate Mach bootstrap namespace for container-like isolation, command line tool: simctl
Simulator running an iOS/tvOS/watchOS personality on macOS, uses sandboxing and a separate Mach bootstrap namespace for container-like isolation; installable simulators as disk images in /Library/Developer/CoreSimulator/Images; command line tool: simctl
SIP System Integrity Protection or rootless mode; collection of kernel-level security restrictions regarding file system modification, unsigned Kexts, Taskport access, NVRAM access, DTrace; /System/Library/Sandbox/rootless.conf; command line tool: csrutil, rootless-init
Site Association signed files in .well-known directory on websites; equivalent to Entitlements for websites, associates domains with app IDs for Universal Links; command line tool: swcutil
SKP Sealed Key Protection; measurement of system state (boot chain IMG4 manifests, BPR, Boot Policy data, UID key, user passcode) to derive Keybag keys
Symptoms network diagnostics; Symptoms.framework; /var/networkd/db/netusage.sqlite; launchd service: com.apple.symptomsd (invoked by kernel through host special port 27)
Synced Defaults simple key-value store for applications, no user control over data; can use iCloud key-value backend (old) or Manatee container (new, marked as com.apple.kvs) as storage; launchd service: com.apple.syncdefaultsd; locally stored in ~/Library/SyncedPreferences
System Configuration SystemConfiguration.framework; launchd service: com.apple.configd; command line tool: scutil
System Extension user-level components formerly in the kernel; currently either a DriverKit, Network, or Endpoint Security extension; /System/DriverKit, /System/Library/DriverExtensions; command line tool: systemextensionsctl; launchd services: com.apple.sysextd, com.apple.nesessionmanager, com.apple.endpointsecurity.endpointsecurityd
System Extension user-level components formerly in the kernel; currently either a DriverKit, Network, or Endpoint Security extension; /System/DriverKit, /System/Library/DriverExtensions; command line tool: systemextensionsctl; launchd services: com.apple.sysextd, com.apple.nesessionmanager, com.apple.endpointsecurity.endpointsecurityd; command line tool: eslogger
System Policy Gatekeeper; policy engine for application launches and kext loading, malware signatures from /Library/Apple/System/Library/CoreServices/XProtect.bundle; /var/db/SystemPolicy; launchd service: com.apple.security.syspolicy (invoked by kernel through host special port 29); command line tool: spctl
TAL Transparent App Lifecycle; process for macOS apps started and stopped independently of the user launching and quitting app; also handles session restore across reboots; ~/Library/Saved Application State; launchd service: com.apple.talagent
Taskport Mach kernel concept for ptrace-like access to task internals; access policy implemented by daemon; launchd service: com.apple.taskgated (invoked by kernel through task special port 9); command line tool: DevToolsSecurity
Translocation app binary copied on launch to dedicated location; initiated by Launch Services for security (prevents path traversal for apps quarantined by System Policy) or path normalization (iOS apps do not expect to be moved, but can be moved on macOS)
TTS Text To Speech, command line tool: say; /System/Library/Speech; synthesizer engines: MacinTalk (historic), Polyglot (phoneme-based?), Gryphon (current, DNN-based?)
TTS Text To Speech, neural-network-based synthesis engine (Gryphon); command line tool: say; /System/Library/Speech, /System/Library/TTSPlugins
TVML TV Markup Language; declarative UI language for TV apps; TVMLKit.framework
Ubiquity iCloud Drive; codename Bladerunner, uses CloudKit; CloudDocs.framework; launchd service: com.apple.bird; locally stored in ~/Library/Mobile Documents (was supposed to move to Library/CloudStorage/iCloud Drive but this was reverted)
UID unique ID key, used as root key for cryptographic subsystems, generated during manufacturing by SEP and fused into hardware, only accessible by SEP
Unified Logging system-wide logging and Activity tracking; launchd service: com.apple.logd, com.apple.diagnosticd; command line tool: log; /dev/oslog; data stored in /var/db/diagnostics, support files in /var/db/uuidtext
USD Universal Scene Description; storage format for 3D assets; /usr/lib/usd
User Activity abstraction for deep-linking into apps with structured context (people, places); used for Universal Links (schema.org on websites), Handoff, Parsec (app links in search), Siri Shortcuts, Quick Note (context awareness), Proactive; UserActivity.framework; launchd service: com.apple.coreservices.useractivityd
User Notifications user interface for notification center; launchd service: com.apple.usernoted
UTI Uniform Type Identifiers; system for document types; file extensions and MIME types are mapped to UTIs, UTIs form a conformance graph, apps register their UTIs with Launch Services; /System/Library/CoreServices/CoreTypes.bundle; also Apple’s hardware devices are represented as UTIs
@@ -299,7 +314,7 @@ Viceroy video conferencing used by FaceTime and ReplayKit; ViceroyTrace.framewor
VSDB volume status database; /var/db/volinfo.database; command line tool: vsdbutil
Waldo selects edge servers based on approximate location, part of Private Relay, seen in NSP
WFS WebDAV File Sharing; built-in file sharing with Apache; /etc/wfs; command line tool: wfsctl
Widgets content excerpt from apps; provided via a timeline of view hierarchies, configuration uses Intents, technically very similar to complications on watch face; extension point: com.apple.widgetkit-extension
Widgets content excerpt from apps; provided via a timeline of view hierarchies, configuration uses Intents; visible on home screen, lock screen, as live activities, as watch complications; WidgetKit.framework; extension point: com.apple.widgetkit-extension
Willow HomeKit; end-to-end-encrypted communication protocol and API for IoT-accessories; pairing with SRP using code printed on device, credential sync by CKKS, transported over Alloy, remote access using Apple TV as proxy; launchd service: com.apple.homed
Workflow Shortcuts; user-programmable system-wide automation, built-in triggers cause a chain of actions to run; actions are synthesized from User Activities and Intents provided by apps; WorkflowKit.framework, ActionKit.framework; locally stored in ~/Library/Shortcuts; launchd service: com.apple.siriactionsd (voice-triggered shortcuts); command line tool: shortcuts
xART eXtended Anti-Replay Technology; persistent storage for SEP, used by Mesa; /System/Volumes/xarts; launchd service: com.apple.xartstorageremoted; command line tool: xartutil
1
Term
Description
5
AAC
Automatic Assessment Configuration; AutomaticAssessmentConfiguration.framework; puts device in a locked mode for exam-style test applications
6
AAT
Apple Advanced Typography; font format and rendering engine
Apple Connect Device External? ACDEClient.framework, old two-step verification, derived from a company-internal AppleConnect system? server: appleconnect.apple.comApple Connect Device External? ACDEClient.framework, old two-step verification, derived from a company-internal AppleConnect system?
9
ACFS
Apple Clustered File System; deprecated file system for Xsan; acfs.framework
10
Acoustic ID
Siri feature to recognize songs
11
Activation
cryptographic check-in with iCloud to lock devices reported by the user as lost; verified by iBoot; MobileActivationMacOS.framework; launchd service: com.apple.mobileactivationd; servers: humb.apple.com, albert.apple.com
12
Activity
jobs, coarse-grained work units of applications; tracked by the system across XPC, bears a QoS class for scheduling; low-level mechanism not to be confused with User Activity
13
AE
Apple Events; messaging system to invoke application functionality; CoreServices.framework/AE.framework; launchd services: com.apple.coreservices.appleevents, com.apple.AEServer (AE over network)
14
Aegir
astronomy watch face and lock screen; /System/Library/CoreServices/AegirProxyApp.app
15
AGC
Apple Graphics Control, management of multiple displays and display port connections; launchd service: com.apple.displaypolicyd
16
AHAP
Apple Haptic Audio Pattern; file format for simultaneous audio and haptic data; CoreHaptics.framework
17
AIR
Apple Intermediate Representation; synthetic bytecode architecture target for GPU binary toolchain
substrate for communication between user devices over Bluetooth and devices to iCloud, implemented over IDS; /System/Library/IdentityServices/ServiceDefinitions; launchd service: com.apple.identityservicesd
51
AWD
Apple Wireless Diagnostics, sends system telemetry to Apple; CoreAnalytics.framework, WirelessDiagnostics.framework; launchd services: com.apple.awdd, com.apple.analyticsd
52
AWDL
Apple Wireless Direct Link; secondary WiFi interface that runs in parallel to an active WiFi access point connection, similar to WiFi Direct (p2p interface), uses a randomized MAC, used for peer-to-peer networking: AirDrop, AirPlay; DeviceToDeviceManager.framework
53
Bezel
on-screen overlays for hardware volume buttons, screen brightness, Bluetooth HID, and others; /Library/Application Support/Apple/BezelServices, launchd services: com.apple.loginwindow, com.apple.OSDUIHelper
sandboxed sanitization process for untrusted iMessage input; BlastDoor.framework
57
BOM
Bill of Materials; format to store contents of installer Packages; command line tool: lsbom
67
Carousel
derivative of SpringBoard for Watch home screen, watch face, and notification center
68
Celestial
media streaming used by ReplayKit for game broadcasts; Celestial.framework
69
Certificates
validity checked using CRLs, OCSP stapling, and transparency logs; /System/Library/Security/Certificates.bundle; launchd services: com.apple.trustd, com.apple.trustd.agent, com.apple.ocspd; command line tool: crlrefresh
70
CHIPChamois
Connected Home over IP; Matter; integrated into HomeKit; CHIP.frameworkStage Manager
71
CHIP
Connected Home over IP; Matter; integrated into HomeKit; CHIPPlugin.framework
72
Circle
cryptographic primitive to exchange public keys of trusted devices of a user, signed by Circle peers; iCloud identity added as additional Circle peer, private key synced across all trusted devices, new devices can pull this key from Secure Backup to join the Circle; per-device Circles stored in CKKS for two-factor accounts (Octagon); KeychainCircle.framework; command line tools: tpctl, otctl (Octagon)
73
CKKS
CloudKit Key Sync, end-to-end secure syncing for credentials, seeded by Circle; currently includes ApplePay, AutoUnlock, CreditCards, DevicePairing, Engram, Health, Home, Manatee, SOS, WiFi and other keys; launchd service: com.apple.secd; command line tool: ckksctl
74
Clarity
customizable accessibility mode for simplified UI; ClarityFoundation.framework
75
Classroom
school teachers can create assignments for student iPads and track progress in Schoolwork app; ClassKit.framework; launchd service: com.apple.studentd
76
Cloud Pairing
part of Alloy, Bluetooth out-of-band pairing over iCloud for Continuity; launchd service: com.apple.BTServer.cloudpairing (cloudpaird)
77
CMAS
Commerial Mobile Alert System, now known as Wireless Emergency Alerts (WEA)
82
Control Center
icons in menu/status bar and Bento Box controls UI, gradually replaces SystemUIServer on macOS; handles incoming AirPlay content; launchd services: com.apple.controlcenter, com.apple.SystemUIServer.agent
Cryptographically sealed Extension of SSV, mount-invisible extension of the root volume, allows lightweight updates as part of Rapid Security Response; /System/Cryptexes (mountpoint), /System/Volumes/Preboot/*/cryptex1/current/*.dmg (disk images)
86
CSR
Configurable Security Restrictions; XNU subsystem that is the basis for SIP
87
CTK
Crypto Token Kit; smart card management, also for the Secure Element on iOS? launchd service: com.apple.ctkd; command line tool: sc_auth
88
CTS
Centralized Task Scheduling; execution of DAS tasks; /System/Library/UserEventPlugins/com.apple.cts.plugin
89
CVMS
Core VM Server/Service? compilation of GPU shaders; launchd service: com.apple.cvmsServ
96
DAV
Distributed Authoring and Versioning; network protocol on top of HTTP for syncing calendars (CalDAV), contacts (CardDAV), and formerly also bookmarks (BookmarkDAV)
97
DCP
Display Co-Processor
98
DEP
Device Enrollment Program; devices check in with Apple during Setup Assistant to query for their enrollment status, retrieve MDM server URL to fetch initial configuration profile
99
Developer Mode
enables launching of self-compiled apps in iOS, rough equivalent to System Policy; command line tool: devmodectl
100
DFR
Dynamic Function Row?, TouchBar; /System/Library/CoreServices/ControlStrip.app; DFRFoundation.framework
101
DFU
Device Firmware Update; special boot mode where iOS has not booted and the system can be installed over the Lightning connection
102
Differential Privacy
crowdsourcing without user tracking; privacy budget for management of anonymity set; used for keyboard words, emoji, Spotlight searches, Parsec deep links, HealthKit usage, Safari telemetry; /System/Library/DifferentialPrivacy; stored in /var/db/DifferentialPrivacy; launchd service: com.apple.dprivacyd
103
Digital Separation
safety check feature to inhibit sharing relationships; DigitalSeparation.framework
104
DND
Do Not Disturb
105
DSID
Destination Signaling Identifier, unique ID for IDS login on a specific device
telemetry collection engine for system and user events, forecasting by machine learning, backend for DAS, Proactive, Relevance, Screen Time, thermal and battery management; /System/Library/DuetKnowledgeBase; CoreDuet.framework, CoreKnowledge.framework, CorePrediction.framework; launchd services: com.apple.coreduetd, com.apple.knowledge-agent
108
Dyld Shared Cache
dynamic linker cache, stores all system libraries in prelinked form, original library files are removed; /System/Library/dyld; command line tool: update_dyld_shared_cachedynamic linker cache, stores all system libraries in prelinked form, original library files are removed; /System/Volumes/Preboot/Cryptexes/OS/System/Library/dyld; command line tools: dyld_info, dyld_usage, update_dyld_shared_cache
109
EAS
Exchange Active Sync; network protocol for accessing Microsoft Exchange servers
110
EDR
Extended Dynamic Range; rendering with transfer function extending beyond sRGB white; implemented natively on XDR displays and by backlight modulation on others; HDRProcessing.framework
111
Energy Impact
unitless metric for per-application energy consumption, machine-specific coefficients; /usr/share/pmenergy, /usr/share/kpep; launchd services: com.apple.sysmond, com.apple.thermald; command line tool: powermetrics
112
Engram
Messages in iCloud; devices store received iMessages in CloudKit; Engram.framework
113
Entitlements
capability-like attributes bound to executables by code signing; some entitlements like App Sandbox restrict ambient authority, some gradually relieve those restrictions (using Seatbelt), some services or system calls grant privilege based on caller entitlements
114
ESS
IDS user directory, public key distribution for iMessage and CloudKit sharing, uses Transparency; server: *.ess.apple.com; launchd service: com.apple.identityservicesd
Event Monitor
simple rules engine for running commands on various systen events; apparently not used by default; /etc/emond.d, /var/db/emondClients; launchd service: com.apple.emond
115
FaceTime
video calls, employs the ICE (establishing peer-to-peer connection), STUN (session credential exchange) and SRTP (encrypted media streaming) protocols; FTServices.framework; launchd services: com.apple.videoconference.camera (avconferenced)
116
FairPlay
DRM system used by app and media stores; CoreADI.framework, CoreFP.framework, CoreLSKD.framework; launchd services: com.apple.adid, com.apple.fairplayd (invoked by kernel through host special port 17), com.apple.lskdd; credentials stored in /var/db/fpsd
117
Family Circle
Family Sharing; launchd services: com.apple.familycircled, com.apple.askpermissiond
122
File Provider
infrastructure and extension system for syncing with cloud providers; placeholder files based on SF_DATALESS attribute in APFS; FileProvider.framework; locally stored in ~/Library/CloudStorage; command line tool: fileproviderctl
123
Find My …
location sharing by explicitly querying devices remotely or collateral beacon detection using Search Party; FMCore.framework, FMF.framework; launchd service: com.apple.icloud.fmfd (find my friends)
124
Firmlink
bi-directional non-symbolic link between the read-only system volume and the data volume, additional symlinks and mountpoints in the root directory are virtually allocated; /usr/share/firmlinks, /etc/synthetic.conf
125
Focus
restriction modes for notification presentation; Focus.framework, DoNotDisturb.framework; local settings in ~/Library/DoNotDisturbrestriction modes for notification presentation; focus filters for in-app display restrictions, communicat by Intents; Focus.framework, DoNotDisturb.framework; local settings in ~/Library/DoNotDisturb
126
FollowUp
user interaction for Secure Backup wrapping with device passcode, CoreFollowUp.framework; launchd service: com.apple.followupd
127
FoundationDB
fundamental iCloud storage database, marketed as CloudKit, separated into containers; records, blobs, and large asset storage with MMCS, server-side continuous queries can trigger push notifications, user management by IDS, sharing between users; PCS keys used for hierarchical zone, record, and asset encryption; CloudKitDaemon.framework; launchd service: com.apple.cloudd; locally stored in ~/Library/Caches/CloudKit, ~/Library/Containers/*/Data/CloudKit; command line tool: cktool
128
FPR
Fast Permission Restrictions; Apple CPU registers to downgrade (old APRRs do bitmasking) or remap (SPRRs since M1) actual permissions of memory pages (the CTRR region) per thread; used for JIT protection and by AMFI to freeze user code after checking
138
HeadBoard
derivative of SpringBoard for tvOS home screen; /Applications/HeadBoard.app, /Applications/PineBoard.app
139
HLS
HTTP Live Streaming
140
HSA
Hardware Security Architecture; version 1 used for two-step verification, SOS with iCSC; version 2 for two-factor authentication, CKKS and Secure Backup with iCDP
141
HSM
Hardware Security Module; HSM fleet runs escrow service for Secure Backup; public keys for authenticating the HSM services in /System/Library/Security/Certificates.bundle/Contents/Resources/AppleESCertificates.plistHardware Security Module; HSM fleet runs escrow service for Secure Backup
boot loader stage after boot ROM or UEFI (macOS on Intel); intermediate Low-Level Bootloader (LLB); DFU mode is implemented here; /System/Library/CoreServices/boot.efi
150
IDV
Identity Verification? Touch ID and Face ID; /System/Library/AccessibilityBundles/CoreIDVUI.axbundle
151
IM
Instant Messaging; usually means iMessage and FaceTime
152
IMG4
boot files (Mach-O binaries or configuration data) with ASN.1 signature, contains RemotePolicy certificate constraints to restrict Boot Policy evaluation
153
Intent
use-case-driven interaction with 3rd-party apps from a host app; used for Siri, Maps, Widgets (configuration); extension points: com.apple.intents-service, com.apple.intents-ui-serviceuse-case-driven interaction with 3rd-party apps from a host app; used for Siri, Maps, Shortcuts, Widgets (configuration); definition file or programmatically using AppIntents.framework; command line tool: appintentsmetadataprocessor (Xcode extracts Intent definition at compile time); extension points: com.apple.intents-service, com.apple.intents-ui-service
154
IOKit
device driver subsystem for in-kernel and DriverKit drivers, command line tool: ioreg
155
Ironwood
dictation, customized on server with selected user data (contacts, app names, music titles, HomeKit names, Siri Shortcut phrases), not tied to Apple ID; SpeechRecognitionCore.framework; server: guzzoni.apple.com
156
ISP
Image Signal Processor; camera imaging circuit in iPhones
157
ITML
iTunes Markup Language; metdata tagging for media services; ITMLKit.framework
158
ITP
Intelligent Tracking Prevention, cross-site tracking defenses in Safari, statistics and user interaction classify sites, cookies are partitioned and access is restricted
159
JARVIS
Just A Rather Very Intelligent Scheduler, Mesos cluster manager for Siri, iCloud, AMS
160
Jellyfish
AnimojiAnimoji; /Applications/Jellyfish.app
161
Jetsam
reclaiming of purgeable memory and termination of apps during memory pressure
162
JSC
JavaScript Core; JavaScriptCore.framework; command line tool: jsc
163
Kalamata
codename for the transition from x86 to ARM-based Apple Silicon
168
Keychain
storage for credentials; launchd service: com.apple.securityd; command line tools: certtool, security, systemkeychain
169
KIP
Kernel Integrity Protection, locking of physical memory pages to prevent changes to kernel
170
Launch Services
management for application launches, association of UTIs to apps, uses Spotlight to update cached info; launchd services: com.apple.coreservices.launchservicesd, com.apple.lsd; CoreServices.framework/LaunchServices.framework; command line tools: lsappinfo, lsregister
171
Live Files
user mode filesystems, currently FAT, ExFAT, NTFS on external storage; UserFS.framework, UVFSXPCService.framework; launchd service: com.apple.filesystems.userfsd
172
Liverpool
PCS codename for CloudKit
173
LKDC
Local Key Distribution Center, Kerberos on client machines
174
LSM
Latent Semantic Mapping, text analysis, used for spam filtering, command line tool: lsm
177
Machine Learning
Vision.framework, Espresso.framework, Futhark.framework, PhotoAnalysis.framework; used for Live Text and Visual Lookup; launchd service: com.apple.mediaanalysisd
178
Madrid
iMessage; /System/Library/Messages
179
Manatee
PCS key for some CloudKit containers are synced via CKKS, so data is unreadable to Apple (credential management codenames: Plesio, Stingray, Cuttlefish)
180
Mandrake
emergency siren on Apple Watch Ultra; /Applications/Mandrake.app
181
Mangrove
transfering UI tiles over XPC; Mangrove.framework, IOSurface.framework
182
Marco
Marco.framework, something about IDS and communication (iMessage, Calls), logging?
183
Marklar
codename from the PowerPC era for the port to x86, served the transition to Intel CPUs
204
Noticeboard
User Notifications for Software Update and App Store, Noticeboard.framework; launchd services: com.apple.noticeboard.state (nbstated), com.apple.noticeboard.agent (nbagent)
205
Notifications
system notification bus, unrelated to the local/remote push notifications; launchd service: com.apple.notifyd, com.apple.kuncd (invoked by kernel through host special port 10); command line tool: notifyutil; complemented by framework-level notification system (CFNotification, NSNotification); launchd services: com.apple.distnoted.xpc.daemon, com.apple.distnoted.xpc.agent
206
NSP
Network Service Proxy; per-app VPN and proxy settings, implements Private Relay; launchd service: com.apple.networkserviceproxy
207
OAH
Rosetta; /usr/libexec/rosettaRosetta; ahead-of-time compiler for Intel code on Apple Silicon; /usr/libexec/rosetta
208
ODR
On-Demand Resources; loaded from App Store; launchd service: com.apple.appstored
209
Onboarding
data protection splash screen shown by service-connected apps; /System/Library/OnBoardingBundles; OnBoardingKit.framework
210
Open Directory
directory service for user, group, and machine management; plugin-based to use different backend stores (LDAP, Active Directory), local accounts in /private/var/db/dslocal; launchd service: com.apple.opendirectoryd; command line tools: dscacheutil, dscl, dsconfigad, dsconfigldap, dseditgroup, dsenableroot, dserr, dsexport, dsimport, dsmemberutil, odutil
213
OTUT
One-Time Unlock Token; security mechanism to allow keybag unwrapping after updates
214
PAC
Pointer Authentication Codes; pointers signed in unused bits to prevent ROP attacks
215
Packages
unit of software installation; command line tools: pkgutil, installer, softwareupdate; launchd services: com.apple.softwareupdated, com.apple.bootinstalld, com.apple.installd, com.apple.system_installd, com.apple.uninstalld; /var/db/softwareupdate, /Library/Apple/System/Library/Receipts (system), /System/Library/Receipts (read-only), /private/var/db/receipts (App Store)
216
Packet Filter
network traffic filtering subsystem from OpenBSD; command line tool: pfctl
217
Parsec
Spotlight web results and searching of crowdsourced User Activity deep links; server: *.smoot.apple.com; launchd services: com.apple.parsecd, com.apple.parsec-fbf (Feedback Flush to Differential Privacy)
218
Password Breach
monitoring of Keychain passwords against a breach database; round-robin matching in fixed-size batches, local match against common leaks, remote match using hash prefix; launchd service: com.apple.Safari.passwordbreachd
219
Pasteboard
storage for cut, copy, and paste; type of content remembered as UTI; launchd service: com.apple.pboard; command line tools: pbcopy, pbpaste
227
Piano Mover
Mail Drop; bulk mail attachments transfered over PCS; not to be confused with storage for iMessage attachments, which uses a CloudKit container
228
Plugin
Extensions, XPC services bundled with apps or frameworks, discovery by Launch Services; launchd service: com.apple.pluginkit.pkd; command line tool: pluginkit
229
PMP
Port Mapping Protocol; Apple alternative to UPnP, Bonjour service: _acp-sync._tcp
battery management like smart charge and power save, learns from Duet and other data; PowerUI.framework; /var/db/PowerUI; launchd service: com.apple.PowerUIAgent
232
Preferences
storage for user-configurable settings; launchd services: com.apple.cfprefsd.xpc.daemon, com.apple.cfprefsd.xpc.agent; stored in Library/Preferences, command line tool: defaults; interaction with Synced Defaults per /System/Library/DefaultsConfigurations
233
Private Relay
two-hop onion routing with one entry and one exit node; Apple operates entry, third-party services operate exit nodes; QUIC for payload, ODoH for DNS, approximate IP geolocation via Waldo; authentication via Attestation, propagated to proxys using RSA blind signatures
256
Seatbelt
process sandbox by filtering system calls; profiles written in SBPL; /System/Library/Sandbox/Profiles, /usr/share/sandbox; default file access policy asks for TCC confirmation before access to folders with user data (like Documents) is allowed; command line tool: sandbox-exec; launchd service: com.apple.sandboxd (invoked by kernel through host special port 14 for logging)
257
Secure Backup
escrow part of CKKS; escrow key individually wrapped with passcodes of trusted devices, stored in HSM to prevent brute forcing, uses SRP so passcodes are not visible to iCloud, limited number of recovery attempts; protocol called Lakitu, uses FollowUp; launchd service: com.apple.SecureBackupDaemon (com.apple.sbd); CloudServices.framework
258
SEP
Secure Enclave Processor; dedicated ARM core for security services, runs L4/Darbat-based sepOS, inline encryption to DRAM, manages AES keys in storage DMA engine, factory-paired channels to Touch ID/Face ID hardware, Secure Element, Neural Engine; SEP can use but not read UID and GID keys; credential verification performed by hardware lockbox with retry count enforcement
259
Sequoia
translation; downloadable language models can run on-device; /Applications/SequoiaTranslator.app, Translation.framework
260
Seymour
Apple Fitness+; workout videos integrated with Watch sensors; SeymourCore.framework
261
SF Symbols
scalable UI symbols; rendered with various color treatments; SFSymbols.framework
262
Sharing
umbrella term for wireless proximity services: AirDrop, Continuity, Instant Hotspot, WiFi sharing; used by loginwindow for Watch unlock; Sharing.framework; launchd service: com.apple.sharingd; also serves connection sharing and remote disk
263
Shazam
music recognition service; ShazamKit.framework; launchd service: com.apple.shazamdaudio (especially music) recognition service; ShazamKit.framework; launchd service: com.apple.shazamd; command line tool: shazam
264
Shoebox
Passbook
265
Sidecar
using iPhone/iPad as Mac accessory: camera for photos and scanning, annotations, external display over low-latency WiFi (llw interface) using avconferenced encoding; SidecarCore.framework; launchd services: com.apple.sidecar-display-agent (SidecarDisplayAgent), com.apple.sidecar-relay (SidecarRelay)using iPhone/iPad as Mac accessory: external camera and microphone (ContinuityCapture), camera for photos and scanning (DocumentCamera.framework), external display over low-latency WiFi (llw interface) using avconferenced encoding; SidecarCore.framework; launchd services: com.apple.sidecar-display-agent (SidecarDisplayAgent), com.apple.sidecar-relay (SidecarRelay)
266
Signpost
telemetry API to report points of interest in code; launchd service: com.apple.signpost.signpost_reporter
267
Simulator
running an iOS/tvOS/watchOS personality on macOS, uses sandboxing and a separate Mach bootstrap namespace for container-like isolation, command line tool: simctlrunning an iOS/tvOS/watchOS personality on macOS, uses sandboxing and a separate Mach bootstrap namespace for container-like isolation; installable simulators as disk images in /Library/Developer/CoreSimulator/Images; command line tool: simctl
268
SIP
System Integrity Protection or rootless mode; collection of kernel-level security restrictions regarding file system modification, unsigned Kexts, Taskport access, NVRAM access, DTrace; /System/Library/Sandbox/rootless.conf; command line tool: csrutil, rootless-init
269
Site Association
signed files in .well-known directory on websites; equivalent to Entitlements for websites, associates domains with app IDs for Universal Links; command line tool: swcutil
270
SKP
Sealed Key Protection; measurement of system state (boot chain IMG4 manifests, BPR, Boot Policy data, UID key, user passcode) to derive Keybag keys
289
Symptoms
network diagnostics; Symptoms.framework; /var/networkd/db/netusage.sqlite; launchd service: com.apple.symptomsd (invoked by kernel through host special port 27)
290
Synced Defaults
simple key-value store for applications, no user control over data; can use iCloud key-value backend (old) or Manatee container (new, marked as com.apple.kvs) as storage; launchd service: com.apple.syncdefaultsd; locally stored in ~/Library/SyncedPreferences
291
System Configuration
SystemConfiguration.framework; launchd service: com.apple.configd; command line tool: scutil
292
System Extension
user-level components formerly in the kernel; currently either a DriverKit, Network, or Endpoint Security extension; /System/DriverKit, /System/Library/DriverExtensions; command line tool: systemextensionsctl; launchd services: com.apple.sysextd, com.apple.nesessionmanager, com.apple.endpointsecurity.endpointsecurityduser-level components formerly in the kernel; currently either a DriverKit, Network, or Endpoint Security extension; /System/DriverKit, /System/Library/DriverExtensions; command line tool: systemextensionsctl; launchd services: com.apple.sysextd, com.apple.nesessionmanager, com.apple.endpointsecurity.endpointsecurityd; command line tool: eslogger
293
System Policy
Gatekeeper; policy engine for application launches and kext loading, malware signatures from /Library/Apple/System/Library/CoreServices/XProtect.bundle; /var/db/SystemPolicy; launchd service: com.apple.security.syspolicy (invoked by kernel through host special port 29); command line tool: spctl
294
TAL
Transparent App Lifecycle; process for macOS apps started and stopped independently of the user launching and quitting app; also handles session restore across reboots; ~/Library/Saved Application State; launchd service: com.apple.talagent
295
Taskport
Mach kernel concept for ptrace-like access to task internals; access policy implemented by daemon; launchd service: com.apple.taskgated (invoked by kernel through task special port 9); command line tool: DevToolsSecurity
300
Translocation
app binary copied on launch to dedicated location; initiated by Launch Services for security (prevents path traversal for apps quarantined by System Policy) or path normalization (iOS apps do not expect to be moved, but can be moved on macOS)
Tatsu Signing Server; online verification for firmware signatures; server: gs.apple.com
303
TTS
Text To Speech, command line tool: say; /System/Library/Speech; synthesizer engines: MacinTalk (historic), Polyglot (phoneme-based?), Gryphon (current, DNN-based?)Text To Speech, neural-network-based synthesis engine (Gryphon); command line tool: say; /System/Library/Speech, /System/Library/TTSPlugins
304
TVML
TV Markup Language; declarative UI language for TV apps; TVMLKit.framework
305
Ubiquity
iCloud Drive; codename Bladerunner, uses CloudKit; CloudDocs.framework; launchd service: com.apple.bird; locally stored in ~/Library/Mobile Documents (was supposed to move to Library/CloudStorage/iCloud Drive but this was reverted)
306
UID
unique ID key, used as root key for cryptographic subsystems, generated during manufacturing by SEP and fused into hardware, only accessible by SEP
307
Unified Logging
system-wide logging and Activity tracking; launchd service: com.apple.logd, com.apple.diagnosticd; command line tool: log; /dev/oslog; data stored in /var/db/diagnostics, support files in /var/db/uuidtext
308
USD
Universal Scene Description; storage format for 3D assets; /usr/lib/usd
309
User Activity
abstraction for deep-linking into apps with structured context (people, places); used for Universal Links (schema.org on websites), Handoff, Parsec (app links in search), Siri Shortcuts, Quick Note (context awareness), Proactive; UserActivity.framework; launchd service: com.apple.coreservices.useractivityd
310
User Notifications
user interface for notification center; launchd service: com.apple.usernoted
311
UTI
Uniform Type Identifiers; system for document types; file extensions and MIME types are mapped to UTIs, UTIs form a conformance graph, apps register their UTIs with Launch Services; /System/Library/CoreServices/CoreTypes.bundle; also Apple’s hardware devices are represented as UTIs
314
VSDB
volume status database; /var/db/volinfo.database; command line tool: vsdbutil
315
Waldo
selects edge servers based on approximate location, part of Private Relay, seen in NSP
316
WFS
WebDAV File Sharing; built-in file sharing with Apache; /etc/wfs; command line tool: wfsctl
317
Widgets
content excerpt from apps; provided via a timeline of view hierarchies, configuration uses Intents, technically very similar to complications on watch face; extension point: com.apple.widgetkit-extensioncontent excerpt from apps; provided via a timeline of view hierarchies, configuration uses Intents; visible on home screen, lock screen, as live activities, as watch complications; WidgetKit.framework; extension point: com.apple.widgetkit-extension
318
Willow
HomeKit; end-to-end-encrypted communication protocol and API for IoT-accessories; pairing with SRP using code printed on device, credential sync by CKKS, transported over Alloy, remote access using Apple TV as proxy; launchd service: com.apple.homed
319
Workflow
Shortcuts; user-programmable system-wide automation, built-in triggers cause a chain of actions to run; actions are synthesized from User Activities and Intents provided by apps; WorkflowKit.framework, ActionKit.framework; locally stored in ~/Library/Shortcuts; launchd service: com.apple.siriactionsd (voice-triggered shortcuts); command line tool: shortcuts
320
xART
eXtended Anti-Replay Technology; persistent storage for SEP, used by Mesa; /System/Volumes/xarts; launchd service: com.apple.xartstorageremoted; command line tool: xartutil
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