[SAump]

I doubt you'll get the response you were looking for tonight.
The situation Pete describes is taken from the MLBUM {or JEA}.
Pete already gave you the situation right out of the book.
Perhaps, you'll find it written in a casebook, the BRD, or J/R.
But you will not find proper umpire mechanics in a rulebook.

It adresses two events differently. Intent of both is the same.
1) miss home, no signal or signal safe and voice "No tag" on a very close play
and 2) miss 1B, signal safe. Why is it different?
Umpire should not alert offense or defense to the possibility of a missed base.
Considered coaching by some and an big no-no by umpires.

Edit: To correct mechanic 1 above by adding empahsis on a play at the plate.