I agree with Andy in that having "None" is a legitimate Option, and if applicable, a valid design route.
I do not agree with Andy in that:
"If you have option buttons on the Form - one of them should always be picked/selected. "
is not quite correct. Although, granted, it is the word "should".
IF the default value of Option buttons (grouped) is blank (Null) - the default state when you create them - then when a userform is displayed, all Option buttons are blank.
However, once ANY Option button is selected, then one of them will always be selected (True). It does not matter which one (that can change), but from then on, one of them will be selected.
Which is why I agree with Andy. "None" is a valid option to be able to set. Selecting "None" becomes an explicit instruction - rather than an implicit state.
Gerry