Is there a G29 command that makes the scan OPTIONAL

I am working on “tuning” my Startup Script for a number of printers…

A while back when I wrote the ORIGINAL scripts, I used a parameter that was SUPPOSED to check if there was ALREADY a valid Matrix, and if there was to SKIP the Scan.

My command looked like
G29 O S1
M420 S1

It no longer seems to appear in the Help or Wiki so I am wondering if it was depricated as it seems to scan every time