I, too, was dismayed that HOS was used. I had absolutely NO idea what words it stood for, although the gist was there. Just try to convince me that this is in common use. I searched the most recent twenty threads in this forum, and it is not mentioned, even once.
I am sorry, but I just don't subscribe to the prevailing notion nowadays that it is up to "the reader to decipher what the writer is saying", rather than "the writer to speak clearly".
