[AtlUmpSteve]

The black is a visual edge that is beyond the dimensions assigned to the plate, therefore it is treated as part of the river. A sliding runner that touches black is similar to touching the side of a base by a runner or fielder.

Take a softball ball, and place it on the black part of a home plate. Place it so that it touches the black but no part touches the white.

Guess what? It can't be done with a 12" softball, it will always touch the edge of the white (with part of the ball hanging over the white, meaning a strike if it didn't hit the plate), too. No matter which way the ball bounces, it touched the plate, and is a ball by rule (and a dead ball when stealing is allowed).

While it shouldn't be said it is part of the plate (because it isn't), it should be treated that way. Simple response when the pitcher/catcher argue it hit the black; you tell them it hit the white, too. Play on.