I am voting this down because "mandatory" doesn't always mean "non-blank". I both like and need the flexibility of the Input Validation formula (or QuerySave event) to do deeper checking for validity.

For example, imagine a form with two fields:

Any new Do-Dads?: [radio: Yes, No]
If, Yes, how many? [number]

The number field need be filled in only if the radio button is set to "Yes", otherwise, it can be blank (or, perhaps, MUST be blank...)

The point is, a simple "mandatory property" doesn't address this situation.

After all, how hard is this to write?: @If( @ThisValue = ""; @False; @True )

-- Grant

@1 Yes, sometimes you do need a deeper level of validation checking, but many times you just want to make sure that the user checks a box or enters something -- anything! -- into a field. In that case, this idea is very useful and not only makes life easier. In cases such as your example were a deeper level of validation would be required then do not flag the field as mandatory and do the normal validation checking in QuerySave or wherever.

I like the general idea, but have something more radical in mind.

lol. Why? From notes version 2.0; validation formula. @IF(fieldname !=""; @Success; @Failure("You must enter a value in this field"));

Lol, Andrew. Did you really think that the great Eknori didn't know that? Did you really get the point that, writing and customizing this message for every single field is just what he would like to get rid of? Did you read Grant's comment, who at least used @ThisValue to make code a little more portable?

Personally, I don't think that this feature would be too useful for me, it just inspired me to a new idea ...

Even better (if you just want a boolean, which is all a "must not be blank" property would provide):

@ThisValue != ""