Here’s a rough idea what it means for a spec to be on the standards track (to me, at least):
If the API or technology is covered by a specification that is anywhere along the formal specification process, it’s on the standards track. These specs are typically in at least a Working Draft (WD) state, or are updates to a previously approved specification. Editor’s Draft (ED) status specifications may also be included if they are updates to existing specs or are already widely implemented to an extent that makes it unlikely not to continue through the specification process.
Working Group Notes are not on the standards track under (to my knowledge) any circumstances. Not until they graduate past that point.