Function MsgLen(var message: message_packet_type):integer;
   EXTERNAL;
{*USER*
 
Return the "valid" (used) length of the message in MESSAGE.  This is
the byte count of the message that is currently used.  This could be
the entire message (currently 206 byte max), or only part of the
message (will be at least 6 bytes).  The length of the message is
computed based on the MESSAGE_PACKET_TYPE ID field, and then on
string length or byte count fields within that message.  For this
reason, the message in MESSAGE must be filled in, complete and valid before
calling this routine, or an improper length may be calculated.
 
*ERROR CODES*
 
There are no errors.
However, any inconsistency found while calculating a message
length will result
in a length of 206 being returned.  206 is the maximum length of any
message, and thus will guarantee that the message contents, regardless
of their format, will be considered valid.  Keep in mind that 206
is a valid message length for a number of messages.
 
}