PROCEDURE OpnDbg(fnam: PACKED ARRAY [lo..hi: integer] OF char);
   EXTERNAL;
{*USER*
    Open or re-open the debug file. At program startup, logical
    name "RTR$DBG_FILE" is used. Thereafter, parameter 'fnam' may
    specify a new file (or device).
 
    Each time called, the current debug log is closed, and a new one
    opened. If 'fnam' is empty (length = 0), then attempt to translate
    'RTR$DBG_FILE' is made. If translation comes up empty, debug file
    is CLOSED; else, the file named by translation of RTR$DBG_FILE is
    used.
 
    If 'fnam' parameter non-empty, attempt to translate 'fnam' as
    a logical. If translation succeeds, use that as filespec. Else,
    use 'fnam' parameter itself as the filespec.
 
    Can you say 'maximum flexibility'? Sure you can...
 }