Finding a particular character using EDM expression builder/ Having a custom search option in proper

Summary

Finding a particular character using EDM expression builder/ Having a custom search option in properties

Content

Dear Team,

We have a requirement to implement a custom validation check for FCGL application from EDM side. The requirement is to evaluate the 'US Description' property and raise a flag if a 'coma' [,] is found in the description. Using the current set of logical commands\keywords at our disposal in the tool[validation at node type level] can we search for any such character!. I did try using a number of logics like using 'match', 'equal's, 'index of' keywords but to no avail!