FlexFilters
Two so-called FlexFilters are available in WinHex Lab Edition, X-Ways Investigator and X-Ways Forensics. They can target any column in the ordinary directory browser (i.e. not search hit list or event list specific columns) that the user wishes to focus on, with an arbitrary number of substrings, and they can be combined with a logical OR or a logical AND. So this makes them the only filters that can be combined with one another with a logical OR.
For example, these filters are useful if you wish to target files that were created or modified not in a particular contiguous period of time, but generally on certain weekdays or on weekends, i.e. where either of these columns contain the word "Saturday" or "Sunday" in the long date notation format. Also useful whenever the column-specific column filter does not give you as many options as you need (e.g. for Author, Sender, Recipients currently you can only enter one name or address or substring, and with the Description filter you cannot currently specifically target additional hard links that are optionally omitted from certain operations).
The color that indicates that a FlexFilter is active is violet instead of blue, so that it can be better distinguished from a regular column filter. Both FlexFilters come with a NOT option, and they may also target the same column, so that you can achieve results like "show all e-mail messages sent with the name John Doe in the sender field where the sender field does NOT contain the domain name company.com".