Sorry this took so long to resolve (I thought I had real work to do!)

Yes, you're right, but the data model specifies 8 hex digits, so it's a typo in the comment. I've fixed it.

I didn't merge the DAMD-4 code in utils.py, and when I came to finally merge the issue I realised that we do indeed have a problem. Shimono-san correctly fixed the SHA truncation, but he didn't address the filenames.

I specified 64-bit SHA1s; I think that that's plenty and anyway that's the biggest number that we can easily put into fits tables so let's stick to that. Unfortunately, I confused bytes with hexadecimal digits and specified %08x formats, whereas I should have said %016x.

This is a pain. I'd simply truncate the SHA1s to 4 bytes for filenames, except that some of the filenames include objIds, and they are also 64 bits and we can't simply truncate them as they are very far from random.

I think we have to face reality and write out all 16 hex digits in both places – ugly. What do you think?

OK, I went with the 0x016x format and that is what is implemented in the data model and DRP-2D