[Doitsu]

Originally Posted by BKh

I found on line that some regex systems can use $10, $11, etc, but that doesn't seem to work either.

Sigil uses the PCRE2 engine for regex searches, which supports named subpatterns.

For example, if your book contains the string:

abcdefghijkl

you could use the following expression to capture each letter:

Find:

(?<a>a)(?<b>b)(?<c>c)(?<d>d)(?<e>e)(?<f>f)(?<g>g)(?<h>h)(?<i>i)(?<j>j)(?<attr>k)(?<l>l)

Replace:

\g{f}\g{e}\g{d}\g{c}\g{b}\g{a}\g{j}\g{l}\g{attr}

You'll end up with:

fedcbajlk