This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
Use html:multibox instead of html:checkbox. It still produces checkboxes, but is designed to be used with a group of related checkboxes all with the same property name. Below is the link to do documentation.