Procedure SRDA( EFN:Event_Flag );
   EXTERNAL;
{*USER*
 
Pascal-3 procedure to specify or clear a Receive Data AST.  The action
of this routine has been restricted to setting a specified event flag
when the AST fires (a message packet is queued for this task).  You
arm the AST by calling this routine with an event flag f1 thru f96.
(Naturally, if you use group globals, they must have been created already.)
After the AST is armed, the event flag specified will be set whenever a
new packet is queued.  To disarm the AST, call the routine with the
null event flag f0.
 
This routine must reside in memory whenever a packet may arrive, as it
contains code that is executed immediately, regardless of where your
current point of execution is.  In most cases, this means the routine
must reside in the root of your task.
 
The specified event flag is cleared before AST is set up.  Make sure you
check the $DSW on exit to confirm that your AST was indeed set up or cleared.
 
}