How can I validate based on a pattern?

Step-by-step guide

1. Click on Modules.
2. Select the Module with the appropriate form field to add the pattern to.
3. Select the Forms tab.
4. Select Field List button "Create/Update Fields".
5. Use the filter to find field that is intended to add the pattern to.
6. Select edit on the field.
7. Select “Validation” tab.
8. As depicted in the picture below, within the “Pattern” section type:
   
   [0-9] +([,; ] *?[0-9]+)*[,; ]*

Pattern condition as follows: Add multiple Entries.

(Example: A pattern for allowing multiple numbers that are separated by either a, or; [0-9] +([,; ] *?[0-9]+)*[,; ]* - require a comma or semicolon delimited list of numbers.)