Friends, can you help me to understand government guidelines on what constitutes a promotion in service?

1. Are there any court judgments defining promotion in government serivce?
2. Can promotion be divorced from pay. That is if a person is shifted from one post to another post having identical pay band and grade pay, but the classifiction is Group C of the feeder post and Group B of the promoted post will this constitute a promotion even though the posts have absolutely identical pay band and grade pay and there is no consequential benefit in pay on promotion. Again are there any judicial pronouncements on this issue.