Posted on December 20, 2011
This article explains how to create a new field to input credit card numbers without the necessity to write a code. For this task, you need to download and install Virto Custom Mask and Unique Field Validation.
Posted on September 15, 2010
With this example you can create unique identifiers of any complexity in any SharePoint objects. You don’t need any special programming skills or code writing.
Posted on April 22, 2010
SharePoint does not support validating values, and it is not required in some cases. However, if you try to build complex business processes based on entered data,
About the author 
Tatiana Sushchenko is the product owner at VirtoSoftware. She started her IT career with the famous ABBYY Lingvo back in 2006 in Moscow. Then she moved to Microsoft performing strongly in various marketing management roles across Visio, SharePoint, Office 365 and Project for almost 10 years. Tatiana is a graduate of the Institute of Business Studies and holds a mini-MBA degree. She also graduated from Microsoft marketing excellence university.