Inscription number, inscription id, collection index

One inscription usually has three different numbers attached to it, and people lose track of which cat they own because of it. Here is what each one is and which to use when.

Three numbers, one inscription, and no reason anybody should be expected to know the difference.

The inscription id

3cbbdd020f5026a3e71c95868a7a4e87813da32d98af6b1430ffbb79d8ae0b38i57

The reveal transaction's id, then i, then which inscription it was within that transaction. Derived entirely from the transaction, globally unique, and impossible to reassign. This is the identifier. Everything else is a convenience.

The trailing index is why a batch reveal produces …i0 through …i550 from one transaction, and why the number after the i is not a collection position — it is a position within one transaction.

The inscription number

71,651,989

Assigned by indexers in the order inscriptions appeared on chain. It is the number wallets show, because it is short and sortable.

Two things to know. It is not part of Bitcoin — it is an indexer's count, and it has been renumbered before when the rules for what counts as an inscription changed. And consecutive inscription numbers mean nothing about relatedness: the 2,222 cats span a range with roughly 3,400 unrelated inscriptions interleaved through it, made by other people in the same blocks.

The collection index

#57

Position within a collection, assigned by whoever made it. It exists only in the collection's own metadata and means nothing outside it.

This is where the confusion usually comes from, because counting conventions differ. A collection whose metadata names its first item "#0" will often be displayed by marketplaces as "#1", since they number positions from one. The same item is then #0 on the project's site and #1 on a marketplace, and both are right about their own numbering.

Which to use

• Identifying an inscription anywhere: the id. Always.
• Looking it up in your wallet: the inscription number, since that is what wallets show.
• Talking about it inside a community: the collection index, and be ready for the off-by-one.

A tool that asks you to identify an inscription should accept all three and work out which one you gave it — the ranges do not overlap, so there is no ambiguity to resolve. Making somebody learn the difference in order to use something is a design failure, not a user error.