Directive not allowed inside structure definition

You have used a directive inside a STRUC definition block that can't be
used there. For example,

   STRUC x
   mem1 DB  ?
      ORG $+4  ;error, can't use ORG inside STRUC 
   mem2 DW  ?
   ENDS 

Also, when declaring nested structures, you cannot give a name to any that
are nested. For example,

   STRUC foo
      STRUC foo2        ;can't name inside
      ENDS 
   ENDS 

If you want to use a named structure inside another structure, you must
first define the structure and then use that structure name inside the
second structure.