Welcome to the Scriptish wiki!
Scriptish is a fork of Greasemonkey, which is a Firefox extension and the first user script engine. Greasemonkey had long supported Firefox 1.5, and plenty of legacy code still existed. Furthermore, Greasemonkey needed a complete reorganization, and plenty of new features. But unfortunately, development of Greasemonkey has grown stagnant. This is why Scriptish forked off Greasemonkey.
@matchmetadata specified by Google Chrome
@css, and many more.