As described in sections 5.6.2.1/2 of the JSF 2.0 specification a "cc" implicit object is accessible in the EL for
composite components.

following features should be at least available:
1) completion for the object itself
2) completion for cc.attr property - offers all attributes defined in the interface of the page
3) hyperlinking for the cc.attr properties - jumps to the interface
[4]) completion of cc.parent.attr properties - depends on particular nesting of the component in a calling page -
indexed occurances are necessary here. Each attribute would indicate from what component it comes in the right text.