I wanted to summarize the responses to my question regarding searching
the Guidelines and add a few precisions, in case anyone else out there
is spending too much term searching without finding.
First, I appreciate that you have suggested that I search at
rather than at www.tei-c.org for the most up to date (but not yet
definitive) version of the guidelines. There, indeed (like at tei-c),
classes and element are alphabetically organized and easy to access.
Martin added a convenient bookmarklet that eliminates several clicks.
His comment that the text all figure on one line in is important! In
the link below I have substituted the site Lou and Sebastien recommend
to add a tiny surplus value :-) (I've tested my change, it works.)
Finally, Sebastien suggested using Google, which made me grumble at
first as I had certainly tried!
But this comment was very productive, as it made me realize that in
fact I had forgotten to specify that I only wanted to search within
the site address above (see advanced search options or just add
"site:..." as below)
google -- "domains" site:http://tei.oucs.ox.ac.uk/P5/Guidelines-web/en/html/
As such, I was easily able to find @domains in the class att.pointing.group