it's fairly easy to have a single field being unique in order to define a record as being unique in a table. But how to define a record being unique based on more than one field ? This key will not be used to create a relationship, only to ensure a record will not be created twice. Looking in the discussions I found out the suggestion of creating a calculation field whose content is the concatenation of the many fields needed to define a record as unique, but the thing is a calculation field can't be made unique, or I really missed something . This is for FMP 13.