Template:IsValidPageName/doc

This template returns " " if the given page title is valid, or the empty string otherwise. The page does not need to exist in order for the template to return " ". As a convenience, the template treats " " as an invalid page title.

Examples

 * returns " "
 * returns " "
 * returns " "
 * returns " " (even though "-" can exist)
 * returns " "