A few weeks ago, my Lenny system switched over from displaying time in MST
(Mountain Standard Time) to MDT (Mountain Daylight Time). It did this, I
believe, because the switch-over is mandated in the official locale coding
for this region (Colorado). I would like to now how to take a pass on this
switch-over part of the local locale. And how to do it ahead of time, so
that for me, I don't have to find an unwanted task of undoing a unwanted
change waiting on a Sunday morning. My version of what I think OP was
asking for is a variant of locale that does not honor local mandates for
switching to and from summer-time. It is very much a cultural thing.