How to add patients with unknown date of birth

How do I allow a patient to be entered into OpenEMR 5.0.2 for whom the date of birth is not known please?

Hi, its very simple.
Go to administration click on Layout,select Demographics in edit layout field then click on new layout field. Check D.O.B field and change the required field to optional.
Thanks

Ahh yes of-course. Thank you.