Joined: Jul 2015
Posts: 7,336
Likes: 3,199
From: NW Oregon
Bikes: 1982 Trek 930R Custom, '91 Diamondback Ascent w/ XT, XTR updates, Fuji Team Pro CF road flyer, Specialized Sirrus Gravel Convert, '09 Comencal Meta 5.5 XC, '02 Marin MBX500, '84 Gitane Criterium bike
those are "clean out grooves" designed to evacuate built up gritty chain grunge, etc.
the fact that they are now turning into yawning cracks, and that the teeth adjacent to them are in a different plane, is not good... i don't care if "they were designed that way".. not good.
the large ring appears to be lacking shift aids other than old style ramps, too...
modern pins and ramps, with lifting cutouts, will greatly improve shifting to that ring.