There are several differences in the wording of
kedusha within the various
nuschaos. For example, according to
nusach Ashkenaz,
kedusha begins with the words
nekadesh es shimcha, whereas according to the other versions it begins with
nakdishach v'na'aritzach. Someone
davening with a
minyan whose
nusach is different than his regular
nusach is required to recite
kedusha according to the shul's custom. If he began with his regular
nusach, he should switch -- even partway through. Some
poskim permit one to recite it in his regular
nusach if he does so quietly.
(
ס"ק א ו־ח; ביאורים ומוספים דרשו, 4)