Hello,
I discover little by little DO. In this moment, I practice the Rename function.
And in this function, it's spoke about "regular expression".
what does that mean ?
Regular expressions are like wildcards but more powerful (and also more complex and, initially, difficult to understand).
The Wikipedia article may be worth skimming and also contains some links at the bottom to other articles which should serve as a good introduction to regular expressions. (I say 'should' since I haven't checked them but their titles sound appropriate.)
en.wikipedia.org/wiki/Regular_expression
Beware! There are several versions of regular expressions. They all work similarly but may use slightly different rules. The Opus PDF manual describes the rules which Opus uses. Other articles and tutorials may be written for different programs but can still be helpful for learning the basics.