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uts46-file-format.md

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Output file format

Codepoints are stored UTF-8-encoded.

All multibyte integers are little-endian.

8 or 12 bytes ...
Header Data

Header

6 bytes 1 byte 1 byte 4 bytes?
magic number version flags optional crc
  • magic number: "UTS#46" (0x55 0x54 0x53 0x23 0x34 0x36).
  • version: format version (1 byte; currently 0x01).
  • flags: See Flags below.
  • optional crc: A CRC32 of the data section if flags has the has crc bit set.

Flags

7 6 5 4 3 2 1 0
unused has crc compression

  • has crc: If set, there will be a CRC32 of the data section at the end of the header.

  • compression: compression mode of the data. Currently identical to NSData’s compression constants + 1:

      - 0: no compression
  - 1: LZFSE
  - 2: LZ4
  - 3: LZMA
  - 4: ZLIB

Data

The data section is a (possibly-compressed; see Flags) collection of data blocks of the format

[marker][section data] ...

Section data formats:

If marker is characterMap (0xFF):

[codepoint][mapped-codepoint ...][null] ...

If marker is ignoredCharacters (0xFE) or disallowedCharacters (0xFD):

[codepoint-range] ...

If marker is joiningTypes (0xFC):

[type][[codepoint-range] ...]

where type is one of C, D, L, R, or T.

codepoint-range: two codepoints, marking the first and last codepoints of a closed range. Single-codepoint ranges have the same start and end codepoint.