Reject empty field *only if on layout*

Hi All

Five year member; first post!

My database has >1000 fields and hundreds of layouts. In 12 years of running this database, I've not been able to overcome the following (apparently simple) problem and I've decided to put some effort into trying to crack it.

On most layouts, I require each field to be completed and I'd like some validation to check this is the case. However, all layouts only contain a small fraction of possible fields, say 50 on each one. I only want to check that the fields which are present on the layout are completed/not empty. I've been messing with 'validation by calculation' but I don't see a simple way of doing this.

I'm rather fascinated that this does not seem to be an issue for most people as I would have thought this would be reasonably common requirement but lots of searching around suggests this is not the case.

I'd be very grateful for any help.

Thanks.

Phil