Any option to validate fields in Jot without the &validate

Hello!

I create a custom field in my blog for comments using JOT 1.1.4, the field is a date field.

i need to validate that field to receive the right format when people fill it, ex: 12/10/2013
but if the user don't want to fill it, is ok.
The form can be submitted....

The problem is if i use &validate=`"MyEmailField:Invalid format.:date"`

this will convert the field in a required field, but this is not a required field, but must be validated before send the comment.

any ideas?????

Thank you!