Date field that you can also put N/A into

Hi chaps,

I have a bit of a dilemma. I have a bunch of text boxes that are used as date fields ie. set as "dd-mm-yyyy" format. However, they ALSO need to allow "N/A" to be typed/ or pre-filled into them but nothing else.

I'm assuming that the date format needs to be set as javascript rather than in the properties, but is anyone able to point me in the direction of the code I need to use?

Thanks.