note that this command also creates a symbol _struct_XYZ where XYZ is the struct name. This can be used with #ifdef to see if a struct is defined
#IFDEF __@INSIDE_STRUCT@__
#ERROR DFERR_COMP_ILLEGAL_CODE_PLACEMENT "STRUCT command within a STRUCT. Structs cannot be Nested"
#ELSE
#STRU !1
#SREP __@INSIDE_STRUCT@__ |CI1 // lets other commands check that they are inside a struct scope.
#ENDIF