User-defined type identifier and record element names
cannot contain periods. A variable name cannot contain a
period if the part of the name before the period has been
used in an AS usertype clause anywhere in the program.
 
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.