Help interpreting a Perl regular expression

[viniebenet3]

I received SAS code that contains a regular expression and I'm having a hard time understanding it. I need to make some edits to it (output isn't correct), but first I need to know what exactly what it is saying. I've used cheat sheets but it's hard for me to put the whole expression together. Any help would be appreciated!

[data_null__]

Aren't we going to need to see the RegEx?

[PGStats]

SAS version of regular expression pattern matching is documented here

https://documentation.sas.com/?docsetId=lefunctionsref&docsetTarget=p0s9ilagexmjl8n1u7e1t1jfnzlk.htm...