M
Mike Dee
In PCRE there's a toggle for case insensitivity.
In Xnews, it's insensitive by default, and to use case
sensitivity, you must use the switch (?-i) before the regex.
(It's kind of a tricky double negative; -i toggles case
insensitivity off, IOW toggles case sensitivity on.)
In The Regex Coach, there are checkboxes to the right of the GUI
for the PCRE option toggles, and mouse-hovering will show you what
each one does.
OK. Thanks very much »Q«. I had better stop pestering you on this and
do some finding out of my own

You've given me much excellent info to get started with. Thanks.