MEL script 01
souya_ConstrainAutoDuplicate();
   :Overview
     Multiple target objects will be replaced with a source object when this mel is applied
     Replacing source object will inherit the position ,scall and rotation of each target objects
   :Intended use
     Say,when you have multiple bolts on the surface of machine
     and want replace them with other type of bolts
     Replaing all of them manually consumes much time. This mel allows you to do it automatically
   :How to use
     First, select multiple target object, then select a source object.
     Excuting the mel will replace old target objects with the new source object.

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copy all description in the linked window above and paste it in Maya script editor, then source it.
 MEL script 02
souya_selectPointsInXNegativePos();
   :Overview
     Only vertices in -x area(in world axis) will be re-selected
     from vertices currently selected.
     (Vertices on x=0 won't be selected.)
   :Intended use
     To select vertices in -x area easily when doing symmetrical modeling with mass vertices.
   :How to use
     Fist select verices as you need, then excute this mel script.
     Only vertices in -x area(in world axis) will be re-selected.
     This mel can be used for SubDiv vertices and Latice vertices as well.

‚c‚‚—‚Ž‚Œ‚‚‚„
copy all description in the linked window above and paste it in Maya script editor, then source it.