A codec option was added to operations as part of PHPLIB-1182, but never documented. I believe this came up when prepping for the 1.17 release and andreas.braun@mongodb.com said it was intentional to quietly roll out the feature.

Creating this as a tracking ticket to go back and add documentation for these options. We can leave the 1.17 branch as-is to avoid a merge headache after PHPLIB-1275 migrates away from apiargs.