Query for items from more than one tag or collection

Is it possible to query for a list of items belonging to multiple collections or tags by id?

For example, something like /api/items?collection=2,66 that would show items that belong in collection 2 OR that belong to category 66…

We have code in the development version (contributed by @Daniel_KM) for doing just this, querying for multiple collections at once, but it’s not in any version that’s released yet. Look for that in version 2.6.

You can already do this with tags by name.