title: validate 3 textfields representing date of birth
body: <p>I have 3 text box fields. to represent a date</p>
  
  <p>eg 
  DD MM YYYY</p>
  
  <p>how can i validate only correct data is entered into each text box.
  is it a regexpression??</p>
  
  <p><strong>i need to do this inside the ascx/aspx file rather than the .cs codebehind</strong></p>
  
  <p>thanks</p>