You should do a search in the document for the word thread, it's defined
clearly in section 2.2
As a long time reader (but infrequent contributor) to this list, I think
it's time to say that I think your tone on this list could do with some
re-calibration. Consider every interaction as you would any kind of
engagement in a professional setting - try and answer questions yourself
before posting, and treat the creators of the language and documentation
with some respect and courtesy.