Validation Issues

[Vinay]

Hi all,
   I am trying to use validation.xml and validate certain fields. I am not sure what 
kind of constants can be used 
in validation.xml. I am not sure how to use validation.xml to validate input fields.I 
have the following validations so far.
I don't understand the how to use the <constant-value>  tag.

Is there a sample validation.xml somewhere like a reference.

  <constant>
   <constant-name>zip</constant-name>
   <constant-value>^\d{5}(-\d{4})?$</constant-value> <!-- validating five digit zip 
code- 4 digit extension-->
  </constant>
  
  <constant>
   <constant-name>AccountNumber</constant-name>
   <constant-value>^\d{1,10}$</constant-value>  <!-- max
  </constant> 

  <constant> 
   <constant-name>DateofBirth</constant-name>
   <constant-value>^\d{6}$</constant-value>
  </constant>
  
 </global>



Thanks a lot
help appreciated

Vinay