<{$searchform.javascript}> is a Smarty tag.

Somewhere in the module PHP script which loads that form the developer is using the XoopsForm class to build all the form fields and form details. This XoopsForm was assigned to Smarty using the name 'searchform'.

All of the <{$searchform.something}> tags hold some sort of details about the form. <{$searchform.javascript}> will likely include any javascript the developer is using with thier form (most likely for validation).

If you look at the HTML source of the actual page when loaded in XOOPs you'll see that in place of <{$searchform.javascript}> there will probably be a chunk of javascript code.

Hope thats the answer you're looking for.