MDS$MITROOT:[*...] contains all of the MIT-original shared images,
command procedures, IDL procedures, etc for MDSplus.

    (note: any PPPL-original stuff is put in MDS$PPPLROOT:[*...] )

Updates are applied via a backup saveset, created on a VMS cluster
node at MIT and then copied down here:

At MIT:  create the backup saveset on Alpha node DAQA ...
    o Login as GIBNEY
    o Move to [gibney.mdsplus]
    o $ @make_mdsplus_backup_since SINCE_TIME
               "SINCE_TIME" is quoted date-time string.
               Procedure will prompt for SINCE_TIME if not provided.

               Get "SINCE_TIME" from the creation time of the most
               recent saveset PPPL_RES:[mdsplus]mdsplus_since_*.bck

    This creates SCRATCH_DISK:[GIBNEY]MDSPLUS_SINCE_yymmdd.BCK

At PPPL:  node Birch, say:
    o Move to PPPL_RES:[mdsplus]
    o $ ftp daqa.psfc.mit.edu
      FTP> login gibney ...
      FTP> cd scratch_disk:[gibney]
      FTP> type backup                 ! <<< NOTE!
      FTP> get MDSPLUS_SINCE_yymmdd.BCK *
      FTP> quit
    o $ backup MDSPLUS_SINCE_yymmdd.BCK/save MDS$MITROOT:[*...]/log

              --> Watch for "over-quota" messages.  Make sure that
                  all files get copied to MDS$MITROOT

Do a test, even a simple one of just mdsOpen and mdsValue:
    $ idl
    IDL> mdsOpen,'dummydata',-1
    IDL> print,mdsValue('xxx_h409:enabled_mask')