A stem is a symbol that must start with a letter and end with a period, like "FRED."or "A.". The value of a stem is a stem object by default. A stem object is a collection with unique indexes that are character strings. Stem objects are automatically created when a REXX stem variable or REXX compound variable is used. In addition to the items assigned to the collection indexes, a stem object also has a default value that is used for all uninitialized indexes of the collection. You can assign a default value to a stem object and later retrieve this value.