How do I create a local function that isn't visible elsewher

How do I create a local function just like the local variables that aren't visible outside of that particular layout ?

You can't.

Ouch...

Wouldn't it be enough to put the function on a event sheet that is only included in that one layout, but not the others?

If that doesn't work, you can put in a condition to the function "layoutname = "the name of your layout""

Thanks