A page similar to this is used for filters based on the Script filter plug-in. This is displayed when you choose one of those filters in the Filter pop-up menu in the Test Info pane.
These filters all have a description followed by zero or more fields, representing custom variables for the script. The Script plug-in is a very powerful feature, allowing you and others to add an unlimited number of new filters to Simon, that leverage the power of AppleScripts, shell scripts, and other script languages. See the Script filter plug-in for more information.
You can get more scripts, and share ones you create, via the Simon Extras page on the Dejal website. Check it out!