CLARIFICATION [Re: Confused first time Kate user]

On 07/02/2024 09:40 AM, Richard Owlett wrote:

I have a Debian machine with Kate Version 16.08.3 .
 I wish to do a search & replace using regular expressions.
The "Help" menu has led to
https://docs.kde.org/stable5/en/kate/katepart/regular-expressions.html
and
https://docs.kde.org/stable5/en/kate/katepart/regex-patterns.html
 I have strings of the form "XYZn" where n is one to three digits representing values of from 1 to 299. I wish to replace all occurrences with "abc".
 The documents give essentially no examples.
 Help please.
TIA
 

The first paragraph of the first reference explicitly warns:

This Appendix contains a brief but hopefully sufficient and
covering introduction to the world of regular
expressions. It documents regular expressions in the form
available within KatePart, which is not compatible with the regular
expressions of perl, nor with those of for example
grep.

Please note the phrasing "... which is not compatible ...".
This is a personal project. I started searching the web for information on regular expressions. Circumstances require I use this particular machine with its current software ] no updates ;[
My formal background is limited to a single introductory programming course I took as a freshman E.E. student in '61. I learned by doing.
My web reading and a discussion in another forum has may has made me aware that there is more than one way to handle regular expressions.
This time I asked on a "editor" focused group and specified the specific editor I'm using.