SharePoint 2010 distincts between true and TRUE for required field
Today while working with the required field attribute in a list I noticed that SharePoint reacted differently if you write TRUE in upper case. The disitinction is when you try to save a new form and some fields have required="true" instead of required="TRUE" then the lower case variant is not validated on the second postback. So when you first save the form and there are validation errors that are detected server side then on the second postback the required="true" variant is not validated but the required="TRUE" variant is. Strange.