Custom field Validation

As far as I can see there is no option to Validate entries made for custom fields. I believe this would be a particular useful option.

For instance I have custom fields for URL and Email. When a new listing is added there is no option to show an error if someone inadvertently puts an email address in the URL field and vice versa.

This then causes an issue on the listing display page as the content for the URL field is replaced with ‘Visit Link Here’ which then makes the mistake less obvious.