[css3-background] unbound background-clip from -origin in background shorthand

Hi,

The current syntax of the shorthand requires browsers to bound the two property values for background-clip and background-origin[1]:

	<bg-layer> = <bg-image> || <position> [ / <bg-size> ]? || <repeat-style> || <attachment> || <box>{1,2}

Making a short test, it seems that most browsers (with exception of FF) support to have a different order[2]:

	background: border-box none content-box;

The browser stay consistent with the wording: "If two values are present, then the first sets ‘background-origin’ and the second ‘background-clip’."

Should css3-backgrounds be lees restrictive?

Greetings,
Dirk

[1] http://www.w3.org/TR/css3-background/#the-background
[2] http://jsfiddle.net/WbWSF/