Loosely speaking, a profile is a definition of a set of terms. Ideally, a profile includes both machine-readable information and human-readable information. In HTML 4.01 and XHTML 1.0, a few attributes such as the rel attribute do not have a predefined set of values. Instead, the author can provide values according to need, and then use a profile to explain what the values mean. In our case, we have recommended that authors use the value "icon" and a profile that explains that "when we say icon, we mean 'this is a favicon.'"
In Method 1 above, we use the rel attribute with the link element and choose a profile with the profile attribute on the HEAD element.
So I happened to read the above stuff while I was sorting out the favicon syntax in my template. I looked at the server error log to see if my code was functioning and noticed the following error from someone accessing our old forum.
[Sat Mar 21 20:45:40 2015] [error] [client 188.8.131.52] File does not exist: /home/odscon2/public_html/phpBB3/profile.php, referer: http://www.odsc.on.ca/
This all just happened at the same time and made me wonder what the profile thing was all about. It looks to be a solution to a non-existant problem. At the time I thought it might have some bearing on my troubles. A while after posting here in the XF support forum, I sorted the favicon code location and got it working.