A period cannot be used in:
  - The name of a user-defined data type.
  - The name of an element in a user-defined type.
  - The name of a variable dimensioned as a
    user-defined data type.
 
Although variable names can contain periods, it is
recommended that a period be used only as a record variable
separator. If you have programs that use a period in
variable names, you could change them to use mixed-case
instead. For example, variable ALPHA.BETA would become
AlphaBeta.