(continued from above)
Look at the places umpire-in-chief appears in the rule book (I can't quote them all because that makes this post more than 10 times the allowable size).
Rules where UIC is mentioned that CC could be substituted with no change in effect or intent:
1.15(c), 2.00 A CALLED GAME, 2.00 A FORFEITED GAME 2.00 MANAGER, 3.10 (b), 3.11, 3.13, 3.18, 4.10 (a), 4.14, 4.15, 9.04 (b) (1), (4), (6), (7), (9), 9.04(c)
Rules where UIC is mentioned that PU really needs to be responsible:
3.03, 3.06, 3.07m, 3.12, 4.01, 5.01, 6.10, 8.01 (f), 8.02, 8.03, 9.03(a), 9.04 (b) (2), (3), (5), (8)
9.03 (b)