bug#47085: du: why does 'usage' show prefixes 'Z' or 'Y' if they are disallowed?

[Paul Eggert]

On 3/11/21 8:53 PM, L A Walsh wrote:
> Why are those suffixes listed as valid under the program 'usage'
> and manpage, when they are automatically disallowed?

They are valid if your computer has wide-enough integers. As far as I 
know no platform supports Y and only one or two supports Z, but the 
documentation is future-proofing.

Conversely, if you're running on a really small computer that doesn't 
even support 64-bit integers, even 'T' is too wide.

I doubt whether it's worth complicating the manual for this minor 
detail, as the current diagnostic "'Y" too large" is accurate as far as 
it goes.