IMPORTANT NOTE FOR USERS OF VMS PRIOR TO VERSION 4.5

DM and SD should properly open .DIR files shared.  Prior to VMS Version
4.5 and FORTRAN Version 4.6, this causes the programs to crash when they
try to close the files.  

In GET_FILENAMES.FOR and SDTREE_SUBS.FOR, there are 2 places in each program
(4 places total) where the code looks something like this:

        Open(Unit=1, File=Current_Dir_FileName, 
	1	Access = 'SEQUENTIAL', Carriagecontrol = 'NONE',
	2	Recl = 512, RecordType = 'VARIABLE',
	3	NoSpanBlocks, Status='OLD', READONLY, Shared, 
C 	3	NoSpanBlocks, Status='OLD', READONLY, 
	4	IOSTAT = IOX, UserOpen = Is_Dir, ERR=40)  


If you are using Version 4.4 (or earlier) of VMS, you MUST modify the source
by using the commented line (not shared), re-compiling the two modules,
and re-linking the programs.