I am trying to create a Product Information Management system that will track attributes of items.  We sell syringes and want to track the needle length, volume, needle gauge, connection type, syringe type, etc.  The problem is that if I only use a custom field, there is no way to validate the entries.  Someone could enter needle gauge as 21g, 21 ga, 21 gauge, 21g., you get the idea.  Is there any way to validate that besides having a script run through and check every field?