Hello,
I shot 360 bracketed images (sun testing). The number of images per bracket varies (3, 5, or 9).
Is there a tag or metadata or another way to have Darktable group these and identify these groupings.
Thanks in advance.
God bless,
Genesius 
This might not be a limitation of DT, but of Exif, or Exif on certain camera brands and models.
I’m using the metadata notes field with alphanumeric string. I was going to tag them “BRr1 - BR?”. However, I had to start from the last image and move towards the beginning (the better brackets were at the end); therefore, I didn’t know what number to start with.
I set the number of images to 9 across (most of my brackets are 9 images). After I find the set of 9, I edit notes with BR-######-9. The ###### is the time the first bracketed image was taken.
Ex. BR-170326-9
Bracketed 5:03:26 pm 9 images
This will work for now. But if there are other, cleaner solutions, please chime in.
Thanks and God bless,
Genesius
Did you use some sort of auto bracket feature on your camera?
you should dump all the exif data from one of the files and see what is there, on my nikon, there is an EV value that is set differently for each bracket, which makes it relatively straight forward to detect the brackets