All tags are optional but the `d` tag MUST be present. Applications SHOULD use their application or bundle identifier as the `d` tag, which typically is an ID with dots in reverse-domain notation.
For `icon` and `image` tags any URL is valid but a Blossom [BUD-01](https://github.com/hzrd149/blossom/blob/master/buds/01.md#get-sha256---get-blob) endpoint is recommended.
License IDs are SPDX IDs as defined in https://spdx.org/licenses/.
An `a` tag reference to the latest 30063 event SHOULD be present to facilitate discovering the latest release of an app. Similarly, `f` tags SHOULD be included to describe supported platforms that MUST match predefined identifiers.
Platform is defined as the specific underlying system on which the application is executed, a combination of operating system and hardware architecture. We use the `f` tag for this purpose, with the following identifiers loosely based off `uname -sm`:
App authors MAY include their pubkeys as `p` tags and `zap` tags as per [NIP-57 - Appendix G](57.md). This is useful in the case of an author other than the one who signed the event, or multiple authors.
A kind 30063 [release artifact set](51.md) SHOULD have an `a` tag reference back to this event, alongside its references to `"e"` [file metadata](94.md) events.
