With SF 2.4, I just tried {{{standard input|cancel|label=Clear form}}} on a Special:RunQuery form, and discovered the button does not even display. The button would be useful for clearing a form for a user to start over, especially on large or complicated forms.
I was able to work around this shortcoming with the fullurl magic word and a very large query string to create a link that explicitly blanks all form parameters. Without the query string, some browsers will keep the data loaded in the fields.
Version: unspecified
Severity: enhancement