[Tex2002ans]

Originally Posted by grannyGrumpy

I know the regex gurus will have some wonderful black magic to do this, [...]

No black magic, just using a "word boundary" (\b), more explanation can be found here:

http://www.regular-expressions.info/wordboundaries.html

This regex will match all cases of "ID":

\bID\b

I would also recommend using the great Spellcheck that was added into Sigil 0.7.0, which can list every single word in the EPUB.

Tools - Spellcheck - Spellcheck (Alt+Q)

Once at the Spellcheck screen, you can put a checkbox in "Show All Words". Then feel free to find whatever word you are looking for in the list, OR search for it by using the "Filter" box at the top.

You can then double click on the word in the list in order to jump to its position throughout the book.