[otrs] Validation in Process with DynamicFields

Hi, I've a process with several dynamic fields, I need to validate that the combination of the dynamic fields information is not duplicated in other existing ticket in the system. I think I can do it in a Transition, with a custom Transition Validation Module, but I only found the ValidateDemo.pm. Are there other examples of custom validations? my perl skills are not the best. Also if anyone knows a simple way to do this consistency check I'll appreciate the hint. Thanks, Eduardo.