Factorio Forums

LuaSurface::create_entity allows the use of the `type` field for use with underground belts, and that is listed.
However, you can set "input" and "output" on loaders as well, and this isn't listed on the method doc.
I assume this is not intentional, and I'm glad I guessed that it worked and found out, but others may not be as lucky.

Thank you for pointing this out. It also accepts the filter parameter in the same format as inserters. Added to the docs for the next doc release.