Yes, It’s just a general label in these notes. Basically it means any artefact as you suggest … though it does not/should not carry any implications about the copyright standing of the object, although this would need to be made explicit in some way with some sort of licensing statement …. (e.g. CC licenses)

What do you men by OER? Definitions seem to range from any artefact on the Web (eg an image) through to choose complex items with educational meta data.