How to find code for calc field

In our environment, on the sales line form, there is a field called, Sales Line Disc. Exist and I am trying to find out how it is getting populated. I looked up the properties for the field and SourceExpr is set to value LineDiscExists, autocalcfield and UpdateOnAction properties are set to Yes. There is no underlying code for any of the triggers for that field. How do I find out how this value is getting populated.

Thanks

It’s a function of the Sales Line table

Thank you so much. Found it.