set of WEISER test or calibration keys

I've had this set of 10 WEISER keys for a long time but I've never really known *exactly* what they are used for, other than what seems obviously to be some particular process that'd be involved in the keying and/or calibration of new WEISER door locks.

10pcs total, each but the single 'uncut' key blank (would be #E00000) is stamped "E11111" to "E99999" in turn, and each appears to have a slightly deeper uniform cut that'd correspond to its numbers, such that #1 is barely ground but #9 is over halfway ground away. Pic 4 is meant to show how each one relates to its neighbors.

If someone *does* know what they're really for, please leave a comment!! :-) :-) :-)