Files
apple-internals/internals.tsv
Michael Roitzsch 8d62d3e215 formally conform to the TSV file format
• move internals.txt to internals.tsv (bonus: GitHub built-in rendering)
• add a header in the first line
• ignore first line for sort checking
• ignore first line for HTML rendering
2022-01-02 15:02:24 +01:00

46 KiB

1TermDescription
21TROne True Recovery; booting into macOS recovery on Apple Silicon by holding the power button to verify physical presence; enables interaction with SEP to change Boot Policy
3AAApple account
4AACAutomatic Assessment Configuration; AutomaticAssessmentConfiguration.framework; puts device in a locked mode for exam-style test applications
5AATApple Advanced Typography; font format and rendering engine
6Accountslaunchd service: com.apple.accountsd; /System/Library/Accounts
7ACDEApple Connect Device External? ACDEClient.framework, old two-step verification, derived from a company-internal AppleConnect system? server: appleconnect.apple.com
8ACFSApple Clustered File System; deprecated file system for Xsan; acfs.framework
9Acoustic IDSiri feature to recognize songs
10Activationcryptographic 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
11Activityjobs, 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
12AEApple Events; messaging system to invoke application functionality; CoreServices.framework/AE.framework; launchd services: com.apple.coreservices.appleevents, com.apple.AEServer (AE over network)
13AEAApple Encrypted Archive; command line tool: aea
14AGCApple Graphics Control, management of multiple displays and display port connections; launchd service: com.apple.displaypolicyd
15AIRApple Intermediate Representation; synthetic bytecode architecture target for GPU binary toolchain
16ALFApplication-Level Firewall, launchd service: com.apple.alf (socketfilterfw)
17Alloysubstrate for communication between user devices over Bluetooth and devices to iCloud, implemented over IDS; /System/Library/IdentityServices/ServiceDefinitions; launchd service: com.apple.identityservicesd
18ALSAmbient Light Sensor, AmbientDisplay.framework
19AmberSwift UI; SwiftUI.framework
20AMFIApple Mobile File Integrity, checks code integrity based on code signature, stronger enforcement with hardened runtime, validates entitlement restrictions; launchd service: com.apple.MobileFileIntegrity (amfid, invoked by kernel through host special port 18); disabled by setting amfi_get_out_of_my_way=0x1 in boot-args
21AMPApple Media Protocol? former parts of iTunes for iPod and iOS device access in Finder, Home Sharing; AMPDevices.framework, AMPSharing.framework; launchd services: com.apple.AMPDeviceDiscoveryAgent, com.apple.AMPDevicesAgent, com.apple.amp.mediasharingd
22AMPAsynchronous Multiprocessing; performance and power-efficiency cores on Apple Silicon
23AMSApple Media Services; formerly the iTunes stores and media services: App Stores, Apple Music, Apple TV, iCloud media library, Apple Podcasts, Podcast sync, Books Store, Books sync; AppleMediaServices.framework; server: phobos.apple.com
24AMXApple Matrix Extension; ARM instruction set extension for matrix operations
25Anisettetwo-factor authentication creates security codes on trusted devices using TOTP, probably using Circle keys, checked by HSA; AuthKit.framework; launchd service: com.apple.akd
26AOPAlways On Processor, part of Apple SoCs, runs RTKit as operating system
27AOSApple Online Services? historical name for iCloud
28Apachebuilt-in web server; command line tool: apachectl
29APFSApple File System; copy-on-write file system with support for volume space-sharing, per-file encryption, and snapshots
30APNSApple Push Notification service, server infrastructure for remote push notifications over a single connection, clients subscribe to push topics, can be authenticated by app (remote notifications), device (Find My …), or Apple ID login (DSID); credentials in apsd keychain; launchd service: com.apple.apsd; server: push.apple.com
31App Napquiescence detection for applications and corresponding self-demotion in scheduler parameters, implemented within application frameworks and RunningBoard, listens for occlusion notifications from WindowServer
32App SandboxSeatbelt-based sandbox for apps; /System/Library/Sandbox/Profiles/application.sb; enabled with com.apple.security.app-sandbox entitlement; launchd service: com.apple.secinitd
33AppleCareextended warranty; NewDeviceOutreach.framework; launchd service: com.apple.ndoagent
34APTAdaptive Picture Timing? ProMotion; dynamic screen updates with 120Hz base frequency; AppleDisplayTCONControl.framework
35ASLApple System Logger, superseded by Unified Logging; /etc/asl; stored in /var/log/asl; launchd service: com.apple.syslogd; command line tool: syslog
36ASRApple Software Restore; restore entire volumes from sources like disk images (HDI, SIU), also restores based on APFS snapshots and snapshot deltas; command line tool: asr
37Assertionspower state management allowing applications to prevent sleeping; launchd service: com.apple.powerd; command line tools: caffeinate, pmset
38Assessmentchecking of System Policy; term also used for AAC
39Asset Cachediscretionary caching server for Mobile Assets, Packages, iOS updates, App Store content, ODR, MMCS data; launchd services: com.apple.AssetCache.builtin, com.apple.AssetCacheLocatorService, com.apple.AssetCacheManagerService, com.apple.AssetCacheTetheratorService; command line tools: AssetCacheLocatorUtil, AssetCacheManagerUtil, AssetCacheTetheratorUtil
40AssistantSiri; dictation and semantic understanding, Intent is communicated to and enacted on the client, uses TTS; /System/Library/Assistant, AssistantServices.framework; server: *.siri.apple.com
41ATSApp Transport Security, sandbox mechanism only allowing TLS-secured connections
42ATSUIApple Type Services for Unicode Imaging; rendering engine superseded by CoreText.framework, font management; ApplicationServices.framework/ATS.framework; launchd service: com.apple.xtyped (fontd); command line tools: atsutil
43ATTApp Tracking Transparency; apps declare user tracking on app store
44Attestationcryptographic proof of a genuine SEP; used for web authentication and app attestation; DeviceCheck.framework; online service signs a GID-based challenge response? used to pair RemoteXPC channel? stripped down variant used to securely identify Touch ID keyboards
45Authorizationdiscretionary access control policies for high-level services; similar to PAM; policy stored in /var/db/auth.db
46AvatarMemoji and Animoji (face tracking); AvatarKit.framework
47AVBAudio Video Bridging, low-latency audio over Ethernet; launchd service: com.apple.avbdeviced; command line tool: avbdiagnose, avbutil
48AWDApple Wireless Diagnostics, sends system telemetry to Apple; CoreAnalytics.framework, WirelessDiagnostics.framework; launchd services: com.apple.awdd, com.apple.analyticsd
49AWDLApple 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
50Bezelon-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
51BiomeCloudKit-based datastream and sync engine; BiomeStreams.framework, BiomeSync.framework; launchd services: com.apple.BiomeAgent, com.apple.biomesyncd
52Blast Doorsandboxed sanitization process for untrusted iMessage input; BlastDoor.framework
53BOMBill of Materials; format to store contents of installer Packages; command line tool: lsbom
54BonjourmDNS; launchd service: com.apple.mDNSResponder.reloaded; command line tool: dns-sd
55Boot Cachedisk cache pre-heating at boot time with typically loaded applications; /var/db/BootCaches; launchd service: com.apple.warmd
56Boot Policydecides by signature check which OSes can be booted, boot-time equivalent for System Policy; LocalPolicy stores user settings, configurable from 1TR, stored by SEP, enforced by iBoot; command line tools: bputil, kmutil (to enroll custom kernels)
57BPRBoot Progress Register; set-only flags to track boot mode (normal, DFU, recovery), part of Keybag class key derivation within SEP, so passcode-protected keys are inaccessible in DFU and recovery
58BridgeT2 ARM CPU in Intel Macs to drive Touch Bar and Boot Policy; runs bridgeOS, a derivative of watchOS; boots the platform and the Intel CPU, communication from macOS uses RemoteXPC; launchd service: com.apple.multiversed; /System/Library/MultiversePlugins
59Brookhand washing encouragement on watch; BrookServices.framework
60Bulletin Boardapplication push notification management, aggregates local and remote push notifications; BulletinBoard.framework
61Cache Deletecleanup for various caches; /System/Library/CacheDelete; launchd service: com.apple.cache_delete (deleted)
62CAMLCore Animation Markup Language; XML file format for layers, shapes and animations
63Carouselderivative of SpringBoard for Watch home screen, watch face, and notification center
64Celestialmedia streaming used by ReplayKit for game broadcasts; Celestial.framework
65Certificatesvalidity 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
66Circlecryptographic primitive to exchange public keys of all trusted devices of one user, signed by all Circle peers; iCloud identity keypair as an additional Circle peer, triggers countersigning from all trusted devices, private key synced across all trusted devices, new devices can pull this key from Secure Backup to join the Circle; used by CKKS; KeychainCircle.framework; command line tools: tpctl, otctl (Octagon trust is newer?)
67CKKSCloudKit Key Sync, end-to-end secure syncing for credentials, seeded by Circle, transferred items stored ephemerally using OTR protocol; currently includes ApplePay, AutoUnlock, CreditCards, DevicePairing, Engram, Health, Home, Manatee, SOS, WiFi and other keys; launchd service: com.apple.secd; command line tool: ckksctl
68Classroomlaunchd service: com.apple.studentd
69Cloud Pairingpart of Alloy, Bluetooth out-of-band pairing over iCloud for Continuity; launchd service: com.apple.BTServer.cloudpairing (cloudpaird)
70CMASCommerial Mobile Alert System, now known as Wireless Emergency Alerts (WEA)
71Commpageuser-mapped kernel data, like vdso/vsyscall on Linux; mapped at 0x7fffffe00000
72Communications Filterrecipient blocking for iMessage, FaceTime, Mail; launchd service: com.apple.cmfsyncagent
73CompanioniPhone that is paired with Watch; communication uses Alloy over IPsec over Bluetooth
74Continuityumbrella term for Handoff, Sidecar, SMS relay, Universal Clipboard, Watch unlock, WiFi call relay and others; SMS relay works by proxying to iMessage, other services use Alloy
75Control Centericons 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
76CPMLCorePrediction Machine Learning; CPMLBestShim.framework
77CRDConference Room Display; Apple TV mode
78CTKCrypto Token Kit; smart card management, also for the Secure Element on iOS? launchd service: com.apple.ctkd; command line tool: sc_auth
79CTSCentralized Task Scheduling; execution of DAS tasks; /System/Library/UserEventPlugins/com.apple.cts.plugin
80CVMSCore VM Server/Service? compilation of GPU shaders; launchd service: com.apple.cvmsServ
81DAAPDigital Audio Access Protocol; used by Home Sharing (with Rapport token) and by the Remote app to control Apple TV (with pairing token); payload unencrypted; DAAPKit.framework; Bonjour services: _atc._tcp, _home-sharing._tcp, _mediaremotetv._tcp, _touch-able._tcp
82Daily BriefingSiri giving an overview of information for the day; SiriDailyBriefingInternal.framework
83DARTDMA Address Relocation Table; IOMMU implementation in Apple silicon, positioned in front of peripheral devices, offers sub-page protection; SART: streaming variant for high-throughput devices (like NVMe)
84DASDuet Activity Scheduler; scheduling policy engine behind NSBackgroundActivityScheduler and XPC activities; /System/Library/DuetActivityScheduler; launchd service: com.apple.dasd
85Data Detectorstext analysis to highlight phone numbers, street addresses, and the like; DataDetectors.framework
86Data Vaultdirectories with the UF_DATAVAULT special flag; CSR limits access to one application
87DAVDistributed Authoring and Versioning; network protocol on top of HTTP for syncing calendars (CalDAV), contacts (CardDAV), and formerly also bookmarks (BookmarkDAV)
88DEPDevice 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
89DFRDynamic Function Row?, TouchBar; /System/Library/CoreServices/ControlStrip.app; DFRFoundation.framework
90DFUDevice Firmware Update; special boot mode where iOS has not booted and the system can be installed over the Lightning connection
91Differential Privacycrowdsourcing 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
92DNDDo Not Disturb
93Domain Associationsigned files in .well-known directory on websites; equivalent to Entitlements for websites
94DSIDDestination Signaling Identifier, unique ID for IDS login on a specific device
95DTracesystem-wide tracing infrastructure, command line tools: dtrace, *.d, dappprof, dapptrace, dtruss, errinfo, execsnoop, fddist, fs_usage, imptrace, iopattern, iopending, iosnoop, iotop, lastwords, latency, opensnoop, plockstat, rwsnoop, sampleproc, sc_usage, topsyscall, topsysproc
96Duettelemetry 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
97Dyld Shared Cachedynamic linker cache, stores all system libraries in prelinked form, original library files are removed; /System/Library/dyld; command line tool: update_dyld_shared_cache
98EASExchange Active Sync; network protocol for accessing Microsoft Exchange servers
99EDRExtended Dynamic Range; rendering with transfer function extending beyond sRGB white; implemented natively on XDR displays and by backlight modulation on others; HDRProcessing.framework
100Energy Impactunitless 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
101EngramMessages in iCloud; devices store received iMessages in CloudKit; Engram.framework
102Entitlementscapability-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
103ESSIDS user directory, public key distribution for iMessage and CloudKit sharing, uses Transparency; server: *.ess.apple.com; launchd service: com.apple.identityservicesd
104Event Monitorsimple 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
105FaceTimevideo 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)
106FairPlayDRM 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
107Family CircleFamily Sharing; launchd services: com.apple.familycircled, com.apple.askpermissiond
108FDEFull Disk Encryption, FileVault; command line tool: fdesetup, sysadminctl
109FDRFactory Data/Device Reset? ensures that no downgrades are performed? servers: skl.apple.com, gg.apple.com; /System/Library/FDR
110FeldsparApple News; Silex.framework
111FiDESFi? Distributed Evaluation Service? aggregates Differential Privacy data for unlinkability? maybe private federated learning? used for emoji, Suggestions, Dictation; /System/Library/DistributedEvaluation; DistributedEvaluation.framework; server: fides-pol.apple.com
112Find 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)
113Firmlinkbi-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
114Focusrestriction modes for notification presentation; Focus.framework, DoNotDisturb.framework; local settings in ~/Library/DoNotDisturb
115FollowUpuser interaction for Secure Backup wrapping with device passcode, CoreFollowUp.framework; launchd service: com.apple.followupd
116FoundationDBfundamental 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
117FPRFast Permission Restrictions; Apple CPU registers to downgrade (old APRRs do bitmasking) or remap (SPRRs since M1) actual permissions of memory pages per thread; used for JIT protection and by AMFI to freeze user code after checking
118FUDFirmware Update Daemon; /var/db/fud; launchd service: com.apple.MobileAccessoryUpdater
119GIDgroup ID key, shared across all devices of the same SoC generation, derived keys are used to prove device type over the network, only accessible by SEP
120GizmoApple Watch; watch settings managed by Companion; /Applications/Bridge.app, /System/Library/BridgeManifests
121Group ActivitiesSharePlay; sharing of media content and programmatic state over FaceTime calls; GroupActivities.framework, CopresenceCore.framework; launchd service: com.apple.telephonyutilities.callservicesd
122GSSGeneric Security Service; part of Kerberos; GSS.framework; launchd service: com.apple.gssd (invoked by kernel through host special port 19); command line tool: gsstool
123GXFGuarded Execution Feature/Fault, additional exception levels on Apple Silicon, lateral to the usual exception levels; page tables remain the same, but interpretation of permission bits changes by way of FPR, genter and gexit instructions; implements lightweight intra-address-space protection contexts
124HAPHome Automation Protocol; CoreHAP.framework
125HDAHigh Definition Audio; HDAInterface.framework
126HDIHard Disk Image; command line tool: hdiutil
127HeadBoardderivative of SpringBoard for tvOS home screen; /Applications/HeadBoard.app, /Applications/PineBoard.app
128HLSHTTP Live Streaming
129HSAHardware Security Architecture; version 1 used for two-step verification, SOS with iCSC; version 2 for two-factor authentication, CKKS and Secure Backup with iCDP
130HSMHardware 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
131HyperioniCloud Photos, uses CloudKit; launchd service: com.apple.cloudphotod; command line tool: cpldiagnose
132IAPiPod Accessory Protocol; IAP.framework
133iBootboot 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
134iCDPiCloud Data Protection, codename for a set of enhancements to iCloud privacy: device passcodes used as iCSC for Secure Backup, root keys for CKKS-enabled services only synced between devices and not stored at Apple; launchd service: com.apple.cdpd
135iCloudumbrella term for a conglomerate of services, consists of FoundationDB containers with PCS views for key management, supported by CKKS; uses IDS and APNS; some services under the iCloud name are actually served by AMS, IMAP, or DAV
136iCSCiCloud Security Code, credential wrapping for Secure Backup, previously used a separate code, with HSA2/iCDP uses device passcodes
137IDAMInter-Device Audio and MIDI; audio connection between devices
138IDSIdentity Service, also IDMS, Apple ID identity management for all of Apple’s online services; APNS topics for signaling and messaging, see also Alloy, ESS, FaceTime, iMessage; authentication to services with Kerberos
139IMInstant Messaging; usually means iMessage and FaceTime
140IMG4boot files (Mach-O binaries or configuration data) with ASN.1 signature, contains RemotePolicy certificate constraints to restrict Boot Policy evaluation
141Intentuse-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
142IOKitdevice driver subsystem for in-kernel and DriverKit drivers, command line tool: ioreg
143Ironwooddictation, 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
144ISPImage Signal Processor; camera imaging circuit in iPhones
145ITMLiTunes Markup Language; metdata tagging for media services; ITMLKit.framework
146ITPIntelligent Tracking Prevention, cross-site tracking defenses in Safari, statistics and user interaction classify sites, cookies are partitioned and access is restricted
147JARVISJust A Rather Very Intelligent Scheduler, Mesos cluster manager for Siri, iCloud, AMS
148JellyfishAnimoji
149Jetsamreclaiming of purgeable memory and termination of apps during memory pressure
150JSCJavaScript Core; JavaScriptCore.framework; command line tool: jsc
151Kalamatacodename for the transition from x86 to ARM-based Apple Silicon
152Kerberossingle-sign-on mechanism; Heimdal.framework; command line tools: kinit, ktutil
153Kextkernel extension mechanism, loaded at boot time as part of a Kext Collection; /Library/Extensions, /Library/StagedExtensions (for user approval), /System/Library/Extensions; command line tool: kextutil (manages deprecated runtime loading)
154Kext Collectionprelinked sets of kernel extensions; /System/Library/KernelCollections (for boot and system kexts), /Library/KernelCollections (for auxiliary third-party kexts); the latter is only loaded at a lower-security Boot Policy; launchd service: com.apple.kernelmanagerd (invoked by kernel through host special port 15); command line tool: kmutil
155Keybagstorage of protection class keys for Keychain and filesystem, protected by SEP using SKP; stored in user.kb; launchd services: com.apple.mobile.keybagd, com.apple.securityd_service, com.apple.secd
156Keychainstorage for credentials; launchd service: com.apple.securityd; command line tools: certtool, security, systemkeychain
157KIPKernel Integrity Protection, locking of physical memory pages to prevent changes to kernel
158Launch Servicesmanagement 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
159LiverpoolPCS codename for CloudKit
160LKDCLocal Key Distribution Center, Kerberos on client machines
161LSMLatent Semantic Mapping, text analysis, used for spam filtering, command line tool: lsm
162Mac Buddyhistoric name for Setup Assistant
163MAC PolicyMandatory Access Control subsystem in XNU, based on TrustedBSD, implements policy hooks for restricted kernel operations; current policies: AMFI, Seatbelt, Quarantine, CSR
164Machine LearningVision.framework, Espresso.framework, Futhark.framework, PhotoAnalysis.framework
165MadridiMessage; /System/Library/Messages
166ManateePCS key for some CloudKit containers are synced via CKKS, so data is unreadable to Apple (credential management codenames: Plesio, Stingray, Cuttlefish)
167Mangrovetransfering UI tiles over XPC; Mangrove.framework, IOSurface.framework
168MarcoMarco.framework, something about IDS and communication (iMessage, Calls), logging?
169Marklarcodename from the PowerPC era for the port to x86, served the transition to Intel CPUs
170MarzipanCatalyst; port of iOS frameworks to macOS, Catalyst apps are iOS apps with additional API to adapt macOS UI idioms; /System/iOSSupport; integration using UIKit system process; launchd service: com.apple.uikitsystemapp; input remapping by /Library/Apple/Library/Bundles/InputAlternatives.bundle
171MCXManaged Client for OS X, preference management for settings from configuration profiles, /Library/Managed Preferences, command line tools: mcxquery, mcxrefresh
172MDMMobile Device Management; server software to manage fleets of iOS and macOS devices; uses configuration profiles to manage preferences; ConfigurationProfiles.framework
173MDSModule Directory Services, ancient part of the old security APIs (CSDA, CSSM)
174Memory Debugginguses Taskport; command line tools: heap, leaks, malloc_history, stringdups, vmmap
175MesaTouch ID; /Library/Catacomb; /var/db/bkad.db
176MetadataSpotlight; file indexing on macOS; CoreServices.framework/Metadata.framework, CoreServices.framework/SearchKit.framework; stored in .Spotlight-V100; launchd service: com.apple.metadata.mds; command line tools: mddiagnose, mdfind, mdimport, mdls, mdutil; in addition to auto-indexing, apps can explicitly register searchable items; CoreSpotlight.framework; launchd service: com.apple.corespotlightd
177MMCSMobileMe Chunk Storage, used by iCloud, splits blobs into chunks and stores them at Apple/AWS/GCP with convergent encryption (content hash as key); MMCS.framework
178Mobileprefix for iOS
179Mobile Assetsdemand-downloaded system components like fonts, dictionaries, linguistic data; stored in /System/Library/Assets; launchd services: com.apple.languageassetd (language-dependent assets), com.apple.mobileassetd; server: mesu.apple.com
180Mobile Deviceconnectivity to iOS devices over USB or WiFi (AirTrafficHost) for syning, development, and debugging; MobileDevice.framework; launchd service: com.apple.usbmuxd; Bonjour service: _apple-mobdev2._tcp
181MOCManaged Object Context; Core Data object space
182Mondrianphoto collage arrangement in Photos.app; Mondrian.framework
183MRTMalware Removal Tool; /Library/Apple/System/Library/CoreServices/MRT.app
184Multipeer Connectivityad-hoc networking; Bonjour for discovery; WiFi, AWDL, Bluetooth, or Ethernet as transport; optional encryption and certificate-based authentication; MultipeerConnectivity.framework
185Nanoprefix for watchOS
186Neural Enginehardware accelerator for neural network operations; ANECompiler.framework, ANEServices.framework; launchd service: com.apple.aned
187Newtonfall detection on watchOS
188NLPNatural Language Processing; NLP.framework; related to mecabra libraries, a linguistic engine for Chinese and Japanese; /usr/share/mecabra, /usr/share/tokenizer
189Notarizationapp security scan by Apple; cryptographic proof stapled to code signature, tested at launch by System Policy; for non-notarized apps sends code hash to Apple; command line tools: altool, notarytool, stapler
190NoticeboardUser Notifications for Software Update and App Store, Noticeboard.framework; launchd services: com.apple.noticeboard.state (nbstated), com.apple.noticeboard.agent (nbagent)
191Notificationssystem 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
192NSPNetwork Service Proxy; per-app VPN and proxy settings, implements Private Relay; launchd service: com.apple.networkserviceproxy
193OAHRosetta; /usr/libexec/rosetta
194ODROn-Demand Resources; loaded from App Store; launchd service: com.apple.appstored
195Onboardingdata protection splash screen shown by service-connected apps; /System/Library/OnBoardingBundles; OnBoardingKit.framework
196Open Directorydirectory 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
197Opuscreate slide shows from photos; Slideshows.framework
198OSAOpen Scripting Architecture; scripting of applications from different fontend languages (currently AppleScript and JavaScript); backed by Apple Events; command line tools: osacompile, osadecompile, osalang, osascript, sdef, sdp
199OTUTOne-Time Unlock Token; security mechanism to allow keybag unwrapping after updates
200PACPointer Authentication Codes; pointers signed in unused bits to prevent ROP attacks
201Packagesunit 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)
202ParsecSpotlight 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)
203Password Breachmonitoring 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
204Pasteboardstorage for cut, copy, and paste; type of content remembered as UTI; launchd service: com.apple.pboard; command line tools: pbcopy, pbpaste
205PCSProtected Cloud Storage; key management for separate iCloud storage compartments (PCS calls them views), each can contain FoundationDB plus bulk data stored by MMCS; see also iCDP, CKKS, Manatee; ProtectedCloudStorage.framework; /System/Library/Preferences/ProtectedCloudStorage; command line tool: pcsstatus
206PCSCPersonal Computer Smart Card; PCSC.framework, uses CTK
207PDEPrint Dialog Extension; old name, not a proper Extension
208Pegasuspicture-in-picture video playback; Pegasus.framework (iOS), PIP.framework (macOS)
209PepperUI elements for Watch home screen and Chat, like Quickboard (canned replies), Animoji; PepperUICore.framework
210Personaseparation of sub-user-identities, like when using a private and managed Apple account; PersonaKit.framework; ~/Library/Personas; /System/Library/UserManagement; command line tool: umtool
211PHASEspatial audio processing; PHASE.framework
212Piano MoverMail Drop; bulk mail attachments transfered over PCS; not to be confused with storage for iMessage attachments, which uses a CloudKit container
213PluginExtensions, XPC services bundled with apps or frameworks, discovery by Launch Services; launchd service: com.apple.pluginkit.pkd; command line tool: pluginkit
214PMPPort Mapping Protocol; Apple alternative to UPnP, Bonjour service: _acp-sync._tcp
215PowerUIbattery management like smart charge and power save, learns from Duet and other data; PowerUI.framework; /var/db/PowerUI; launchd service: com.apple.PowerUIAgent
216Preferencesstorage 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
217Private Relaytwo-hop onion routing with one entry and one exit node; Apple operates entry, third-party services operate exit nodes; approximate IP geolocation via Waldo
218Proactiveumbrella term for suggestions and completions based on Duet forecasting and User Activity context, also marketed as Siri features; PersonalizationPortrait.framework
219QoS Classesinheritable property for Activities; semantic priorities, influences scheduling parameters; initially set at user-level, priority inheritance within GCD queues and across XPC in kernel?
220Quaggaframework for QR and barcode decoding; Quagga.framework
221Quick Actionextension type for quick interaction with foreign content within a host app; extension points: com.apple.services, com.apple.ui-services
222Quick Lookfile preview and thumbnail generation; comand line tool: qlmanage
223RAOPRemote Audio Output Protocol, AirPlay; Bonjour service: _raop._tcp
224Rapportdevice pairing by proximity using Alloy, with PIN entry, or using iCloud; once paired, devices can access services; used for HomeKit, HomePod, AirPlay, Home Sharing, SideCar; Rapport.framework; launchd service: com.apple.rapportd; Bonjour service: _companion-link._tcp
225Recentsrecently used items (not files) in various applications, synced with Synced Defaults; CoreRecents.framework, /System/Library/Recents; launchd service: com.apple.recentsd
226Relevance Enginebackend for Siri suggestions (for example of Siri Shortcuts), Widget smart stacks (also Siri watch face); consumes Duet knowledge and app-provided timelines with relevance hints; /System/Library/RelevanceEngine; launchd service: com.apple.relevanced
227RemoteXPCconnection to a non-SoC-integrated SEP like Bridge; uses HTTP/2 over a network interface, Bridge connected over USB, secured using Attestation; RemoteServiceDiscovery.framework, TrustedAccessory.framework; launchd service: com.apple.remoted, com.apple.tracd; command line tool: remotectl
228Revisionsdocument autosave and auto-versioning; stored in .DocumentRevisions-V100; GenerationalStorage.framework; launchd service: com.apple.revisiond
229Routinefrequently visited locations on iOS, interacts with Duet; launchd service: com.apple.routined
230RTCReal-time Telemetry and Crash reporting; RTCReporting.framework; launchd service: com.apple.rtcreportingd
231RunningBoardruntime management of apps, paradigm: app as service process invoked by system, check-in by frameworks, handles process assertions (frontmost app, see App Nap), memory pressure (see Jetsam) and compute resources (GPU), replacement for TAL?; launchd service: com.apple.runningboardd; /System/Library/LifecyclePolicy, /System/Library/RunningBoard
232SBPLSandbox Profile Language; a TinyScheme-based embedded DSL for Seatbelt profiles
233SCIPSystem Coprocessor Integrity Protection; like KIP, but for SEP, ISP, Motion coprocessor
234Screen ReaderVoiceOver and Braille; /System/Library/ScreenReader; ScreenReader.framework
235Screen Timedigital wellbeing and parental controls system, uses Device Management as policy engine, self-enforced within the application by frameworks; DeviceActivity.framework, ManagedSettings.framework, FamilyControls.framework; launchd services: com.apple.ScreenTimeAgent, com.apple.dmd
236SDBSQL Database; CoreSDB.framework, used by iCloud communication
237Search Partyportion of Find My service for offline devices; devices emit public part of rotating key pair via Bluetooth LE, other devices encrypt current location with this key and send to Apple, private key shared over CloudKit
238Seatbeltprocess 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)
239Secure Backupescrow 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
240SEPSecure 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
241SeymourApple Fitness+; workout videos integrated with Watch sensors; SeymourCore.framework
242Sharingumbrella 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
243Shazammusic recognition service; ShazamKit.framework; launchd service: com.apple.shazamd
244ShoeboxPassbook
245Sidecarusing 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)
246Signposttelemetry API to report points of interest in code; launchd service: com.apple.signpost.signpost_reporter
247Simulatorrunning an iOS/tvOS/watchOS personality on macOS, uses sandboxing and a separate Mach bootstrap namespace for container-like isolation, command line tool: simctl
248SIPSystem 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
249SKPSealed Key Protection; measurement of system state (boot chain IMG4 manifests, BPR, Boot Policy data, UID key, user passcode) to derive Keybag keys
250SKSSecure Key Store; handling of keybag keys within the SEP
251SkyLightWindowServer; SkyLight.framework
252Skywalknetwork subsystem in XNU, links together actual technologies (Bluetooth, WiFi, Thunderbolt) and interfaces/tunnels; transacts in nexus (for conduits) and agent (for endpoints) objects; DriverKit network drivers use Skywalk; command line tool: skywalkctl
253Social GamingGame Center; multiplayer gaming services on top of CloudKit, shared storage and low-latency multicast for multiplayer sessions; launchd service: com.apple.gamed
254Sock PuppetWatch interaction that requires Companion device
255SOSSecure Object Sync; syncing backend for iCloud Keychain, not to be confused with the emergency call feature; transferred items previously staged in Synced Defaults, now uses CKKS; launchd services: com.apple.secd (access to local keychain), com.apple.security.cloudkeychainproxy3 (connects to Synced Defaults), com.apple.security.keychain-circle-notification
256SPISystem Private Interface; /System/Library/PrivateFrameworks
257SpringBoardiOS home screen; like Dock (Launchpad, Mission Control, desktop picture), Control Center, SystemUIServer (menu extras icons), loginwindow (lock screen), and WindowServer (compositor) on macOS; /System/Library/CoreServices/SpringBoard.app, /Applications/PreBoard.app, BaseBoard.framework, FrontBoard.framework, SplashBoard.framework; launchd service: com.apple.backboardd (compositor)
258SPRRShadow Permission Remap Register? feature of Apple Silicon to dynamically reintepret page permissions
259SRPSecure Remote Password; standard cryptographic protocol for proving knowledge of a secret such that attackers cannot brute-force the secret; AppleSRP.framework
260SSOSingle Sign-On
261SSVSigned System Volume, als called Authenticated Root Volume (ARV); macOS boots from blessed read-only APFS snapshot, merkle-tree and root-hash stored in Preboot volume; modifications require disabling root authentication with csrutil from recovery, then the live filesystem can be mounted, modified, and re-blessed; command line tools: apfs_systemsnapshot, bless, csrutil
262StarkCarPlay
263StockholmSecure Element in Apple SoCs, a processor running crypto protocols on keys it protects; used for Apple Pay and Car Key; related codenames: Icefall, Warsaw
264Storage Managementfreeing up disk space by managing bulky items; UI in System Information.app; StorageManagement.framework; launchd service: com.apple.diskspaced; extension point: com.apple.storagemanagement; extends Cache Delete service
265Suggestionssemantic analysis of mails and websites to suggest contacts, calendar events and the like; launchd services: com.apple.suggestd, com.apple.reversetemplated; custom JavaScript parsers in /System/Library/AssetsV2/com_apple_MobileAsset_CoreSuggestions
266Symbolsdebug symbols for backtraces; CoreSymbolication.framework; launchd services: com.apple.coresymbolicationd; command line tools: symbols, symbolscache
267Symptomsnetwork diagnostics; Symptoms.framework; /var/networkd/db/netusage.sqlite; launchd service: com.apple.symptomsd (invoked by kernel through host special port 27)
268Synced Defaultssimple 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
269System ConfigurationSystemConfiguration.framework; launchd service: com.apple.configd; command line tool: scutil
270System Extensionuser-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
271System PolicyGatekeeper; 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
272TALTransparent 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
273TaskportMach 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
274TCCTransparency, Consent, and Control; user control over app access to privacy-related services (kTCCService*); TCC.framework; launchd services: com.apple.tccd, com.apple.tccd.system; command line tool: tccutil; stored in /Library/Application Support/com.apple.TCC, ~/Library/Application Support/com.apple.TCC, /var/db/locationd (for kTCCServiceLocation)
275Time Machineautomatic backup service, command line tools: tmdiagnose, tmutil
276Tin CanWalkie Talkie on watchOS
277Tonesringtones; ToneLibrary.framework
278Translocationapp 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)
279Transparencykey transparency for ESS keys? Transparency.framework; launchd service: com.apple.transparencyd; server: init-kt.apple.com
280TTSText To Speech, command line tool: say; /System/Library/Speech; synthesizer engines: MacinTalk (historic), Polyglot (phoneme-based?), Gryphon (current, DNN-based?)
281TVMLTV Markup Language; declarative UI language for TV apps; TVMLKit.framework
282UbiquityiCloud Drive; codename Bladerunner, uses CloudKit; CloudDocs.framework; command line tools: fileproviderctl; launchd service: com.apple.bird (iclouddrive-agent); locally stored in ~/Library/Mobile Documents (was supposed to move to Library/CloudStorage/iCloud Drive and iclouddrivectl but this was reverted)
283UIDunique ID key, used as root key for cryptographic subsystems, generated during manufacturing by SEP and fused into hardware, only accessible by SEP
284Unified Loggingsystem-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
285User Activityabstraction behind deep-linking into apps with structured context data (people, places); used for Universal Links (with schema.org on websites), Handoff, Parsec, Siri Shortcuts, Proactive; UserActivity.framework; launchd service: com.apple.coreservices.useractivityd
286User Notificationsuser interface for notification center; launchd service: com.apple.usernoted
287UTIUniform 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
288VAVideo Acceleration; AppleGVA.framework, AppleVA.framework, AppleVPA.framework
289Viceroyvideo conferencing used by FaceTime and ReplayKit; ViceroyTrace.framework
290VSDBvolume status database; /var/db/volinfo.database; command line tool: vsdbutil
291Waldoselects edge servers based on approximate location, part of Private Relay, seen in NSP
292WFSWebDAV File Sharing; built-in file sharing with Apache; /etc/wfs; command line tool: wfsctl
293Widgetscontent 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
294WillowHomeKit; 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
295WorkflowShortcuts; user-programmable system-wide automation, built-in triggers and actions, extensible with User Activities and Intents; WorkflowKit.framework, ActionKit.framework; locally stored in ~/Library/Shortcuts; launchd service: com.apple.siriactionsd (voice-triggered shortcuts); command line tool: shortcuts
296xARTeXtended Anti-Replay Technology; persistent storage for SEP, used by Mesa; /System/Volumes/xarts; launchd service: com.apple.xartstorageremoted; command line tool: xartutil
297XCSXcode Server; continuous integration server; command line tools: xcscontrol, xcsdiagnose