What does a layer's "tattoo" mean?

[Ofnuts]

(02-08-2021, 04:11 PM)ChameleonScales Wrote: Thank you!
Glad I asked because it's exactly what I was hoping it would be!
I feel like "id" or "uid" (Unique Identifier) would be a more intuitive name for this. What do you think?
Anyway, at least I know now.

There are already IDs in Gimp, but they identify items across loaded images (you won't have two layers/channels/items with the same ID, even if you duplicate the image). And uf you load the image the IDs will likely be different.

By contrast, the "tattoo" is not unique in Gimp, it is unique within an image, and is saved with the image, so if the image is loaded again, you reuse the tattoo to retrieve that same item (how the tattoo is transmitted is another matter).