Since updating to PS v23.0 and Camera Raw v14.0, it appears that Camera Raw now outputs a second sidcar file - in addition to <filename base>.xmp, I now see <filename base>.acr.
I once negelected to move this file along with the raw file and xmp file. When I opened the image again in Camera Raw in the new directory, Camera Raw indicated that the select subject mask was not available and had to be re-run. After re-running the mask it appears to be fine.
Does this .acr file contain information related to the new masks, and, if it is misplaced, can it be reconstructed witout loss of information by rerunning the masks in ACR? I suspect the same situation could occur if a file is edited in ACR, then moved and imported into Lightroom without the .acr sidecar. I've not tried it importing edited files (with our without the .acr sidecar) into LR (Classic) yet.
Environment: MacOS Catalina and Nikon .NEF files, but I doubt this situation is OS or RAW file dependent.
I haven't been able to find any information on this at all.
They are sidecar ai-generated selection masking data. If you used "select sky" and "select subject" and disabled the "embed xmp in DNG" option, they appear. I think the continuous process of updating the selection functions generated with "artificial intelligence" will be stored in these files to reload them quickly instead of recalculating them every time. (Oct 2022) there are two (sky, subject) so far.