Doc for zmodload: What exactly does this mean?

["Bart Schaefer" <schaefer@xxxxxxxxxxxxxxxx>]

     The `-d' option can be used to specify module dependencies.  This
     operation is idempotent regardless of the `-i' option.

I know what "idempotent" usually means, but I can't figure out what it's
supposed to imply in that particular sentence.

-- 
Bart Schaefer                                 Brass Lantern Enterprises
http://www.well.com/user/barts              http://www.brasslantern.com