Confusing / wanting documentation for _in query parameter filter

I am confused by the intended use of the _in filter. The way it is described in the docs , appears that the syntax should look something like id_in=3,6,8 , but the example further down the page is ?id_in=3&id_in=6&id_in=8 , and I can’t tell how that’s different from a regular OR operation.

Typically it is an array, we convert the rest params into an array in the backend. The way this filter is handled was more so for backend usage or GraphQL where you can actually pass in an array.

We are planning a massive rework of the filtering system likely in 2021.