Just got a response from support, who claims that HTML code is not supported in the Request Detail, only BBCode.
However, I find this to be partially, if not wholly inaccurate.
Any feedback on HTML and BBCode use when implementing API?
Here's a screen-cap to illustrate. You can see the mouse-over pop-up is formatted correctly, but the detail field shows the 'br' tag:
Incidentally, I did try the BBCode equivalent [br] for a line break, but it did not create a line break and the tag showed up in the detail, so...
Just to follow up on this, I was able to switch some tags and get it to work properly. I enclosed BEGIN/END text with paragraph tags and the HTML code no longer appeared in the ticket details.
Also, support confirmed that HTML tags showing in the email subject is a bug that will be "resolved in a future release"