Earlier in this chapter, you learned that you could define a specification as Unique, Generic, or Replica. You can ensure that you define the appropriate type of specification for a given field by following these simple guidelines:
Use a Unique specification for any field that will appear only once within the entire database or for a field that serves as a primary key.
Use a Generic specification for a field that serves as a template for other fields within the database. Remember to use a nonspecific field name and element settings that are as broad and general as possible.
Use a Replica specification for a field that you base on a given generic field or for a field that serves ...