This document standardizes the treatment given by clients of inline mentions of other events and pubkeys inside the content of `text_note`s.
Clients that want to allow tagged mentions they MUST show an autocomplete component or something analogous to that whenever the user starts typing a special key (for example, "@") or presses some button to include a mention etc -- or these clients can come up with other ways to unambiguously differentiate between mentions and normal text.
Once a mention is identified, for example, the pubkey `27866e9d854c78ae625b867eefdfa9580434bc3e675be08d2acb526610d96fbe`, the client MUST add that pubkey to the `.tags` with the tag `p`, then replace its textual reference (inside `.content`) with the notation `#[index]` in which "index" is equal to the 0-based index of the related tag in the tags array.
The same process applies for mentioning event IDs.
A client that receives a `text_note` event with such `#[index]` mentions in its `.content` CAN do a search-and-replace using the actual contents from the `.tags` array with the actual pubkey or event ID that is mentioned, doing any desired context augmentation (for example, linking to the pubkey or showing a preview of the mentioned event contents) it wants in the process.
Where `#[index]` has an `index` that is outside the range of the tags array or points to a tag that is not an `e` or `p` tag or a tag otherwise declared to support this notation, the client MUST NOT perform such replacement or augmentation, but instead display it as normal text.
