CNMT

This is the metadata file that ends in ".cnmt{.nca}" or "meta0.ncd". This seems to replace the TMD format.

There's at least 9 different filenames used for ".cnmt":

• "Application_{lower-case hex titleID}.cnmt"
• "Patch_{lower-case hex titleID}.cnmt"
• "AddOnContent_{lower-case hex titleID}.cnmt"
• "SystemUpdate_{hex titleID}.cnmt"
• "SystemData_{lower-case hex titleID}.cnmt"
• "SystemProgram_{lower-case hex titleID}.cnmt"
• "BootImagePackage_{lower-case hex titleID}.cnmt"
• "BootImagePackageSafe_{lower-case hex titleID}.cnmt"
• "Delta_{lower-case hex titleID}.cnmt"

It starts with a header:

Offset	Size	Description
0x0	8	Title ID
0x8	4	u32 title-version
0xC	1	Type (see Title Types)
0xD	1
0xE	2	Offset to table relative to the end of this 0x20-byte header.
0x10	2	Number of content entries
0x12	2	Number of meta entries
0x14	12

With SystemUpdate, the 4-bytes at offset 0xE are zero, with the entry-count field located at offset 0x12 instead(header size is the same).

An optional header can follow, depending on the title type.

At the end of the file following the entries is a 0x20-byte block, presumably a hash.

With Patch-format, there's additional data after the end of the entries specified in the header and before the ending hash.

Application header

Offset	Size	Description
0x20	8	Patch Title ID
0x28	8	Minimum system version

Patch header

Offset	Size	Description
0x20	8	Original title ID
0x28	8	Minimum system version

Add-on content header

Offset	Size	Description
0x20	8	Application title ID
0x28	8	Minimum application version

Content records

Each entry is 0x38 bytes:

Offset	Size	Description
0x0	32	Hash
0x20	16	NcaId [same as first 16-bytes of hash]
0x30	6	Size, same as the output from NCM_services#GetSizeFromContentId.
0x36	1	Type (0=Meta, 1=Program, 2=Data, 3=Control, 4=HtmlDocument, 5=LegalInformation, 6=DeltaFragment)
0x37	1

Meta records

Each entry is 0x10 bytes:

Offset	Size	Description
0x0	8	Title ID
0x8	4	Title version
0xC	1	Type (see Title Types)
0xD	1	? bit0 set = don't install?
0xE	2	Unused?

This is used for SystemUpdate, see here: NCM_services#ReadEntryMetaRecords.

Extended data

Patch-type cnmt files include an extended data section.

Offset	Size	Description
0x0	4	Number of previous cnmt entries.
0x4	4	Number of previous delta entries.
0x8	4	Number of delta info entries.
0xC	4	Number of delta application info entries.
0x10	4	Number of previous content entries.
0x14	4	Number of delta content entries.
0x18	4	Unused?
0x1C	0x38*X	Previous cnmt entries
	0x28*X	Previous delta entries
	0x28*X	Delta info entries
	0x34*X	Delta application info entries
	0x18*X	Previous content entries
	0x38*X	Delta content entries. (Standard content records)
	4	Unknown
	4	Unknown
	4	Unknown

Previous cnmt records

Each entry is 0x38 bytes:

Offset	Size	Description
0x0	8	Title ID
0x8	4	Title version
0xC	1	Type (see Title Types)
0xD	3	Unused?
0x10	32	Hash
0x30	2	Unknown
0x32	2	Unused?
0x34	4	Unused?

This contains information on previous metadata files.

Previous delta records

Each entry is 0x28 bytes:

Offset	Size	Description
0x0	8	Old title ID
0x8	8	New title ID
0x10	4	Old title version
0x14	4	New title version
0x18	8	Size
0x20	8	Unused?

This contains information on previous delta patches.

Delta info records

Each entry is 0x28 bytes:

Offset	Size	Description
0x0	8	Old title ID
0x8	8	New title ID
0x10	4	Old title version
0x14	4	New title version
0x18	8	Some sort of index?
0x20	8	Some sort of index?

This contains information on the current delta patch.

Delta application info records

Each entry is 0x34 bytes:

Offset	Size	Description
0x0	16	Old NcaId
0x10	16	New NcaId
0x20	6	Old size
0x26	2	Upper 2 bytes of the new size
0x28	4	Lower 4 bytes of the new size
0x2C	2	Unknown
0x2E	1	Type (see Title Types)
0x2F	1	? bit0 set = don't install?
0x30	4	Unused?

This contains information on how to apply deltas to the previous patch.

Previous content records

Each entry is 0x18 bytes:

Offset	Size	Description
0x0	16	NcaId
0x10	6	Size
0x16	1	Type (see Title Types)
0x17	1

This contains information on previous title content from earlier patches.