Re: [PATCH] Update packfile transfer protocol documentation

"Shawn O. Pearce" [off-list ref] writes:

If its SHA-1 you are talking about, I wanted this to be a MUST
use lowercase, but people screamed about it (Jakub and Ilari
IIRC).  The current C code accepts uppercase due to its use of
get_sha1_hex(), and they wanted to follow the "be liberal in what
you accept" suggestion from other IETF authors.

IIRC, all implementations use lowercase.  We should be able to safely
say MUST produce lowercase, and MUST accept lowercase, and SHOULD
NOT accept uppercase,...

I do not see a point in loosening or tightening the definition
document that is written to describe a protocol of a reference
implementation after the fact.  It is not like producing lowercase
hexdegits is a lot more work on some weird platforms.

Everybody writes in lowercase, expects to see lowercase, and some may
accept uppercase by accident.  I think it is acceptable to describe that
as "MUST produce, MUST accept lc and MAY accept uc", but I do not think it
is even necessary to specifically say "and MAY accept uc".

It is actively wrong to say "SHOULD NOT accept uc"---it won't help
anybody.