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Kind

The kind of a record determines the application that the record is used by. This also determines the nature of the payload.

Kinds are represented by an array of 8 bytes, equivalent to a 64-bit unsigned integer in big endian format.

A kind can be broken into three parts:

Range Meaning
Byte 0-3 Application Identifier, 32-bit unsigned integer in big-endian format
Byte 4-5 Application-Specific Kind, 16-bit unsigned integer in big-endian format
Byte 6-7 Bitflags for record handling

Bitflags are as follows:

Bits 1 and 0:

  • 00 - Unique. All records SHOULD have unique addresses. In the case that multiple records share the same address, all of them MUST be preserved just like Versioned records are (see bits 11 below)
  • 01 - Ephemeral; Servers MUST serve this record to current subscribers, but SHOULD NOT save the record nor serve it later to future subscribers.
  • 10 - Replaceable: Among records with the same address, only the one with the latest timestamp MUST be served by servers, and prior records MUST NOT be served. Note that servers must verify subkey-masterkey relationships in order to allow one subkey to replace an event created by a different subkey.
  • 11 - Versioned: Among records with the same address, all of them remain relevant and should be seen as a version history.

Bits 3 and 2:

  • 00 - Author Only: Servers MUST serve this record only to it's author.
  • 01 - Author + Tagged: Servers MUST serve this record only to it's author and the public keys that are tagged in the record.
  • 10 - RESERVED
  • 11 - Everybody: Servers MAY serve this record to anybody.

Bit 4: If on, the contents of this record are considered to be printable (human readable).

Bits 15-5: RESERVED and MUST be 0