Rockbox

I made an assumption that it was the designed behaviour, as with the volume enum.

It makes sense to me for maximum volume (0db) to have it’s own state, because it represents the line-level output on those targets such as the H1x0 that has a variable level output on the line-out jack.

i.e., I have my volume indicator set in my WPS as:
%?pv<mute|v.v. low|v. low|low|med|high|v. high|v.v. high|line>

For the battery, you could argue that you may want a ‘Full’ or ‘Max’ indicator for the 100% value.

Especially in the case of charging, being able to see 100% on its own is handy.

For WPSes one could readily use the same image for the top two cases so that it appears full, thus mimicing something like this behaviour without a patch, and still allowing the original behaviour in the original case.