PROCEDURE VSDA(Task_Name:Rad56;
               Buff: address;
               Buff_Len:INTEGER;
               EFN:Event_Flag
               );
   EXTERNAL;
{*USER*
 Pascal-3 procedure to send a variable 512-byte max data packet to the
specified task.  The SRDA directive requires that the data packet be
word aligned.  Thus the address supplied in BUFF must be even (word
aligned).
 
EFN is set for the SENDING task. (of course, globals or group globals
may be used). If f0 is specified, no flag is set.
 
Task_Name must be in RAD50 format.
 
The length of the data packet sent is in words.  If LEN is less than
13 (or zero), a default minimum length of 13 words will be used.
 
This procedure directly implements executive directive VSDA$.
 
$DSW holds the directive status on return.
 
}