Thepartition type (orpartition ID) in a partition's entry in the partition table inside amaster boot record (MBR) is a byte value intended to specify thefile system the partition contains or to flag special access methods used to access these partitions (e.g. specialCHS mappings,LBA access, logical mapped geometries, special driver access, hidden partitions, secured or encrypted file systems, etc.).

Lists of assigned partition types to be used in the partition table in the MBR were originally maintained byIBM andMicrosoft internally. When the market of PC operating systems and disk tools grew and liberated, other vendors had a need to assign special partition types to their products as well. As Microsoft neither documented all partition types already assigned by them nor wanted to maintain foreign assignments, third parties started to simply assign partition types on their own behalf in a mostly uncoordinated trial-and-error manner. This led to various conflicting assignments sometimes causing severe compatibility problems between certain products.^[1]

Several industry experts including Hale Landis,Ralf D. Brown, Matthias R. Paul, andAndries E. Brouwer in the 1990s started to research partition types and published (and later synchronized) partition type lists in order to help document the industryde facto standard and thereby reduce the risk of further conflicts. Some of them also actively helped to maintain software dealing with partitions to work with the updated lists, indicated conflicts, devised additional detection methods and work-arounds for vendors, or engaged in coordinating new non-conflictive partition type assignments as well.

It is up to anoperating system'sboot loader orkernel how to interpret the value. So the table specifies whichoperating systems or disk-related products introduced an ID and what file system or special partition type they mapped it to. Partitions with partition types unknown to the software should be treated as reserved but occupied disk storage space which should not be dealt with by the software, save forpartition managers.

While the list is not officially maintained,^[1]new assignments should be coordinated.

In particular temporary partition type assignments for local or experimental projects can utilize type7Fh in order to avoid conflicts with already assigned types. This type was specially reserved for individual use as part of theAlternative OS Development Partition Standard (AODPS) initiative since 2002.^[2]

This is a list of known master boot record partition types onIBM PC compatible computers:

• Disk partitioning § PC partition types
• Extended Boot Record (EBR)
• GUID Partition Table (GPT)
• List of file systems
• Rigid Disk Block (RDB)

• "5.3.2.2. Partition-Tabelle".Anwenderdokumentation - Anleitung für den Systemprogrammierer - MOS DCP 1700(PDF). 3.20 (in German). Dresden, East-Germany:VEB Robotron-Projekt Dresden. 1988-01-29. C3013-0000-0 M3030, Textdiskette DCP1700 T1/2 C3010-9991-2M3020, Disk-Nr.: 5962 /88 ROBOTRON PROJEKT DRESDEN KA2 DD-DS 80*16*256.Archived(PDF) from the original on 2021-08-29. Retrieved2021-12-03. (NB. Has partition IDs for the East-German MS-DOS cloneDCP 1700 (including R/W and R/O), the CP/M-86 cloneSCP 1700, the VENIX cloneMUTOS and the iRMX cloneBOS1810.)

• Disk file systems
• Disk partitions
• DOS technology
• IBM PC compatibles

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