CNMT

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

The official name for CNMT is "PackagedContentMeta".

PackagedContentMetaHeader

This is "nn::ncm::PackagedContentMetaHeader".

Offset	Size	Description
0x0	0x8	Id
0x8	0x4	Version
0xC	0x1	ContentMetaType
0xD	0x1	[17.0.0+] ContentMetaPlatform ([1.0.0-16.1.0] Reserved)
0xE	0x2	ExtendedHeaderSize
0x10	0x2	ContentCount
0x12	0x2	ContentMetaCount
0x14	0x1	ContentMetaAttributes (0=None, 1=IncludesExFatDriver, 2=Rebootless, 4=Compacted)
0x15	0x3	Reserved
0x18	0x4	RequiredDownloadSystemVersion
0x1C	0x4	Reserved

SystemUpdateMetaExtendedHeader

This is "nn::ncm::SystemUpdateMetaExtendedHeader".

Offset	Size	Description
0x0	0x4	ExtendedDataSize

ApplicationMetaExtendedHeader

This is "nn::ncm::ApplicationMetaExtendedHeader".

Offset	Size	Description
0x0	0x8	PatchId
0x8	0x4	RequiredSystemVersion
0xC	0x4	RequiredApplicationVersion

PatchMetaExtendedHeader

This is "nn::ncm::PatchMetaExtendedHeader".

Offset	Size	Description
0x0	0x8	ApplicationId
0x8	0x4	RequiredSystemVersion
0xC	0x4	ExtendedDataSize
0x10	0x8	Reserved

AddOnContentMetaExtendedHeader

This is "nn::ncm::AddOnContentMetaExtendedHeader".

Offset	Size	Description
0x0	0x8	ApplicationId
0x8	0x4	RequiredApplicationVersion
0xC	0x1	[15.0.0+] ContentAccessibilities ([1.0.0-14.1.2] Reserved)
0xD	0x3	Reserved
0x10	0x8	[15.0.0+] DataPatchId

DeltaMetaExtendedHeader

This is "nn::ncm::DeltaMetaExtendedHeader".

Offset	Size	Description
0x0	0x8	ApplicationId
0x8	0x4	ExtendedDataSize
0xC	0x4	Reserved

DataPatchMetaExtendedHeader

This is "nn::ncm::DataPatchMetaExtendedHeader".

This was added with [15.0.0+].

Offset	Size	Description
0x0	0x8	DataId
0x8	0x8	ApplicationId
0x10	0x4	RequiredApplicationVersion
0x14	0x4	ExtendedDataSize
0x18	0x8	Reserved

PackagedContentInfo

This is "nn::ncm::PackagedContentInfo".

Offset	Size	Description
0x0	0x20	Hash (SHA256 of the referenced content)
0x20	0x10	ContentId
0x30	[15.0.0+] 0x5 ([1.0.0-14.1.2] 0x6)	Size
0x35	0x1	[15.0.0+] ContentAttributes
0x36	0x1	ContentType (0=Meta, 1=Program, 2=Data, 3=Control, 4=HtmlDocument, 5=LegalInformation, 6=DeltaFragment)
0x37	0x1	IdOffset

ContentMetaInfo

This is "nn::ncm::ContentMetaInfo".

Offset	Size	Description
0x0	0x8	Id
0x8	0x4	Version
0xC	0x1	ContentMetaType
0xD	0x1	ContentMetaAttributes (0=None, 1=IncludesExFatDriver, 2=Rebootless, 4=Compacted)
0xE	0x2	Reserved

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

SystemUpdateMetaExtendedData

This is "nn::ncm::SystemUpdateMetaExtendedData".

If the Version field is 1, the format is:

Offset	Size	Description
0x0	0x4	Version
0x4	0x4	VariationCount
0x8	0x20 * VariationCount	FirmwareVariationInfo (Version 1)

If the Version field is 2, the format is:

Offset	Size	Description
0x0	0x4	Version
0x4	0x4	VariationCount
0x8	0x4 * VariationCount	FirmwareVariationId
Variable	0x20 * VariationCount	FirmwareVariationInfo (Version 2)
Variable	0x10 * MetaCount (from FirmwareVariationInfo (Version 2))	ContentMetaInfo (if ReferToBase is False)

FirmwareVariationInfo

This is "FirmwareVariationInfo ".

If the Version field is 1, the format is:

Offset	Size	Description
0x0	0x4	FirmwareVariationId
0x4	0x1C	Reserved

If the Version field is 2, the format is:

Offset	Size	Description
0x0	0x1	ReferToBase (0=False, 1=True)
0x1	0x3	Reserved
0x4	0x4	MetaCount
0x8	0x18	Reserved

PatchMetaExtendedData

This is "nn::ncm::PatchMetaExtendedData".

Offset	Size	Description
0x0	0x4	PatchHistoryHeaderCount
0x4	0x4	PatchDeltaHistoryCount
0x8	0x4	PatchDeltaHeaderCount
0xC	0x4	FragmentSetCount
0x10	0x4	PatchHistoryContentInfoCount
0x14	0x4	PatchDeltaPackagedContentInfoCount
0x18	0x4	Reserved
0x1C	0x38 * PatchHistoryHeaderCount	PatchHistoryHeader
Variable	0x28 * PatchDeltaHistoryCount	PatchDeltaHistory
Variable	0x28 * PatchDeltaHeaderCount	PatchDeltaHeader
Variable	0x34 * FragmentSetCount	FragmentSet
Variable	0x18 * PatchHistoryContentInfoCount	PatchHistoryContentInfo (PackagedContentInfo without the Hash entry)
Variable	0x38 * PatchDeltaPackagedContentInfoCount	PatchDeltaPackagedContentInfo
Variable	0x4 * FragmentIndicatorCount (from FragmentSet)	FragmentIndicator

PatchHistoryHeader

This is "nn::ncm::PatchHistoryHeader".

Offset	Size	Description
0x0	0x10	ContentMetaKey
0x10	0x20	Digest
0x30	0x2	ContentInfoCount
0x32	0x6	Reserved

PatchDeltaHistory

This is "nn::ncm::PatchDeltaHistory".

Offset	Size	Description
0x0	0x8	SourcePatchId
0x8	0x8	DestinationPatchId
0x10	0x4	SourceVersion
0x14	0x4	DestinationVersion
0x18	0x8	DownloadSize
0x20	0x8	Reserved

PatchDeltaHeader

This is "nn::ncm::PatchDeltaHeader".

Offset	Size	Description
0x0	0x8	SourcePatchId
0x8	8	DestinationPatchId
0x10	0x4	SourceVersion
0x14	0x4	DestinationVersion
0x18	0x2	FragmentSetCount
0x1A	0x6	Reserved
0x20	0x2	ContentInfoCount
0x22	0x6	Reserved

FragmentSet

This is "nn::ncm::FragmentSet".

Offset	Size	Description
0x0	0x10	SourceContentId
0x10	0x10	DestinationContentId
0x20	0x6	SourceSize
0x26	0x6	DestinationSize
0x2C	0x2	FragmentIndicatorCount
0x2E	0x1	FragmentTargetContentType (0=Meta, 1=Program, 2=Data, 3=Control, 4=HtmlDocument, 5=LegalInformation, 6=DeltaFragment)
0x2F	0x1	UpdateType (0=ApplyAsDelta, 1=Overwrite, 2=Create)
0x30	0x4	Reserved

FragmentIndicator

This is "nn::ncm::FragmentIndicator".

Offset	Size	Description
0x0	0x2	ContentInfoIndex
0x2	0x2	FragmentIndex

DeltaMetaExtendedData

This is "nn::ncm::DeltaMetaExtendedData".

Offset	Size	Description
0x0	0x8	SourcePatchId
0x8	0x8	DestinationPatchId
0x10	0x4	SourceVersion
0x14	0x4	DestinationVersion
0x18	0x2	FragmentSetCount
0x1A	0x6	Reserved
0x20	0x34 * FragmentSetCount	FragmentSet
Variable	0x4 * FragmentIndicatorCount (from FragmentSet)	FragmentIndicator

Digest

Offset	Size	Description
0x0	0x20	Digest

This is a SHA-256 hash always found at the end of the file. The hash is calculated over the CNMT file's contents, but this is only done for the development version of the file which results in its production version counterpart sharing the same hash value.