I thought archetype-based ECS was the standard way to implement an ECS. Typically using bitsets or something to define an archetype.

But I may just not be understanding what an archetype represents exactly. My only real experience with ECS, besides implementing a crude one around 2011 for fun, is EnTT, which specifically advertises itself as not being archetype-based as one of its key differentiators.

Its likely I just don't quite understand archetypes though.