This is used in combination with JavaScript and MVC (hence the ViewData object). If this code is pasted into a MVC View User Control (.ascx) file, it becomes a reusable Select All/Clear control. It was originally written with a C# codebase. It will work in VB as well, with minor changes (i.e. change all square brackets around ViewData to parenthesis). Also, below the closing script tag is code that is used to call the control. Make sure the string value of the first parameter matches the name of the ascx file that contains the script.