Provenance

The owner of an inscription can create child inscriptions, trustlessly establishing the provenance of those children on-chain as having been created by the owner of the parent inscription. This can be used for collections, with the children of a parent inscription being members of the same collection.

Children can themselves have children, allowing for complex hierarchies. For example, an artist might create an inscription representing themselves, with sub inscriptions representing collections that they create, with the children of those sub inscriptions being items in those collections.

Specification

To create a child inscription C with parent inscription P:

• Create an inscribe transaction T as usual for C.
• Spend the parent P in one of the inputs of T.
• Include tag 3, i.e. OP_PUSH 3, in C, with the value of the serialized binary inscription ID of P, serialized as the 32-byte TXID, followed by the four-byte little-endian INDEX, with trailing zeroes omitted.

NB The bytes of a bitcoin transaction ID are reversed in their text representation, so the serialized transaction ID will be in the opposite order.

Example

An example of a child inscription of 000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1fi0:

OP_FALSE
OP_IF
  OP_PUSH "ord"
  OP_PUSH 1
  OP_PUSH "text/plain;charset=utf-8"
  OP_PUSH 3
  OP_PUSH 0x1f1e1d1c1b1a191817161514131211100f0e0d0c0b0a09080706050403020100
  OP_PUSH 0
  OP_PUSH "Hello, world!"
OP_ENDIF

Note that the value of tag 3 is binary, not hex, and that for the child inscription to be recognized as a child, 000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1fi0 must be spent as one of the inputs of the inscribe transaction.

Example encoding of inscription ID 000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1fi255:

OP_FALSE
OP_IF
  …
  OP_PUSH 3
  OP_PUSH 0x1f1e1d1c1b1a191817161514131211100f0e0d0c0b0a09080706050403020100ff
  …
OP_ENDIF

And of inscription ID 000102030405060708090a0b0c0d0e0f101112131415161718191a1b1c1d1e1fi256:

OP_FALSE
OP_IF
  …
  OP_PUSH 3
  OP_PUSH 0x1f1e1d1c1b1a191817161514131211100f0e0d0c0b0a090807060504030201000001
  …
OP_ENDIF

Notes

The tag 3 is used because it is the first available odd tag. Unrecognized odd tags do not make an inscription unbound, so child inscriptions would be recognized and tracked by old versions of ord.

A collection can be closed by burning the collection's parent inscription, which guarantees that no more items in the collection can be issued.