[tex-hyphen] hyphenmins in latex formats

[Karl Berry]

    - If the limits were set in the usual way before loading patterns,
    they would set upper limit on the values that are possible to use 

I don't understand.

As far as I know, the current values for \lefthyphenmin and
\righthyphenmin are used at line-breaking time (\par).  They can be
reset at any time.  I've never seen any concept of a format definition
setting an "upper limit".

They aren't used by \patterns at all.  As far as I can see from tex.web.