Notes:

•Regex settings use .NET Framework regular expressions to search for patterns (e.g., headerLinesRegex defines what a file's header looks like).
 
An online tester like regexplanet.com can help to understand them.

•Regex Named Groups settings are regular expressions that contain named groups
(e.g., seriesUnitColumnHeaderRegexGroups captures a series' unit from the column's header text).
 
Dot Net Perls (the second snippet of code, colored in blue) has a simple example that nicely illustrates capturing a regex named group's value.
 
A named group looks like: (?'name'subexpression), or (?<name>subexpression),
where name is the group's name (and cannot begin with a number or contain punctuation characters),
and subexpression is the pattern to capture.
 
If there is more than one named group, and/or more than one match is found, the agent joins the values using colons (:).

•Regex is case sensitive by default; the (?i) mode modifier may be used to make it case insensitive.