https://musicbrainz.org/relationship/5db276a9-15d2-3955-b5d9-c11f27fd8b44

Based on STYLE-268 I assume this is supposed to be for Events that are hosted by the releasing artist as a launch party for a release (group).  The relationship currently lacks any guidelines indicating when this relationship is or is not appropriate.

I would expect that a massive convention inviting multiple unrelated artists does not qualify as a launch event for any of those artists' releases, and instead, https://musicbrainz.org/relationship/de1f976a-d6af-342d-9220-d2485284e502 should be used.

Example event: https://musicbrainz.org/event/d3feac9b-c727-4332-8732-40376f9dc7ea

Example release group that currently claims a non-launch party as a launch event: https://musicbrainz.org/release-group/0424863e-09d8-415c-97e6-a71c0e0ec764