Viart can do just about any kind of error checking on custom fields that you may want to add to your checkout process. However this often means a good knowledge of regular expressions, something that im sure a lot of viart users will not have.
I've just had to add some expressions to a site I've made, and realised that theres no documentation regarding this in the viart manual!!! (or on the forums as far as I could see!)
A list of example expressions or even a drop down or some update to the interface in the admin for this feature with a list of default/editable example expressions would be fantastic.
For reference, the last expression I wrote today which is very simple but may be of use to someone acts as a maxlength checker, allowing you to check the length of input for your custom field.
The expression for this is: /^[\w\s]{0,50}$/
This allows all standard a-z/A-Z/0-9 characters as well as white space characters. Anything else input, along with a length over a total of 50 characters will cause an error and viart to return the input to the user with a custom error message.
