Regular expression settings defines the regex syntax to use when searching. This can either be the Perl compatible regular expression syntax or the Classic regular expression syntax. See Expression Types for more information.
When searching for text in foreign languages it can often be useful to 'Collate character ranges' which allows characters outside the standard a-z range to be included in the range, e.g. to include the é in Années when using the range [a-z]+
Multi-line Regular Expressions
The Max lines per match sets the maximum number of lines over which a single multi-line regular expression match can be made, and therefore the maximum number of lines FileLocator Pro needs to hold in memory when performing multi-line regular expression matching.