> For the complete documentation index, see [llms.txt](https://docs.catalog.cat/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.catalog.cat/technical-manual/catalog/the-register-action.md).

# The Register Action

*Note*: The register action code be found [here](https://github.com/Yakuhito/slot-machine/blob/master/rue-puzzles/actions/catalog/register.rue) ([Chialisp](https://github.com/Yakuhito/slot-machine/blob/master/puzzles/actions/catalog/register.clsp)).

The register action, as the name suggest, registers a new CATalog entry. This requires a precommitment coin that contains the TAIL hash, the initial NFT owner puzzle hash, as well as refund-related information (CAT maker and CAT maker solution) to be created before.

When the action is run, it:

* Creates a slot that represents the CAT. This prevents future registrations from registering the same TAIL hash.
* Spends the slots representing the new slot's neighbors to assert that they exist, and updates their neighbors so the new structure is: left neighbor <-> new slot <-> right neighbor
* Creates a uniqueness prelauncher for the CAT NFT, whose puzzle contains the TAIL hash. The prelauncher puzzle hash and parent can be used in the future to assert that a given NFT represents a particular CAT asset id (TAIL hash/CATalog entry).
* Consumes the precommitment coin
* Asserts the CAT NFT was correctly created (i.e., it was created to the specified owner)

The action also creates a puzzle announcement. This announcement can be asserted to ensure the dApp singleton is running the right action with the right parameters. For the register action, the announcement prefix, `'r'` , is concatenated to `(sha256tree (tail_hash . initial_nft_owner_ph))`.

*Written by* [*yakuhito*](https://x.com/yakuhito) *from* [*FireAcademy.io*](https://fireacademy.io/) *on Feb 14th, 2025.*


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