nips/100.md

NIP-100
=======

Querying Events by Tags Presence
---------------------------------

`draft` `optional` `author:fernandolguevara` `requires:nip-12`

This NIP allows clients to query events from relays based on the presence or non-presence of specific tags.

### Presense:
The filter condition matches if there is at least one tag name in common with the filter and event.

### Non-Presence:
The filter condition matches if there is at least one tag in the filter that are not present in the event.

Example Subscription Filter
---------------------------

Below are some example filters that demonstrate tag presence and non-presence:

1. Filter to match events with a `g` tag:

```json
{
  "tags": ["g"]
}
```

2. Filter to match events without the presence of the `e` tag:

```json
{
  "tags": ["!e"]
}
```

Suggested Use Cases
-------------------
One of the suggested use cases for this NIP is for location-specific events. Clients can utilize the provided filter example to locate events with specific location-related tags, regardless of how the location information has been stored in the events.