Respected sirs:

I would like the learned members to clarify my doubt. While meditating on SOHAM, it is said in one upanishad that inhale with SO and exhale with HUM. In some other upanishads it is said that inhale with HUM and exhale with SO. Which is correct or both are right . If so, what is the reason for it. Upanishads might be having some reason to say differently at differently places. Thanks and regards,
N.R.Ranganathan.