DOM features
The W3C DOM is currently defined in 3 levels; 1, 2, and 3. Each level is split into several features. DOM 1 and 2 are complete recommendations, but some features of DOM 3 are not yet recommendations (the specifications are still in development).
If a browser supports enough of a feature, it can claim to support that feature by returning true when the hasFeature method is called. To support "enough" of the feature, it must implement the vast majority of objects, methods, and interfaces from that feature. It must implement them to such an extent that it is considered a bug when one is not supported, as opposed to being an intentionally unsupported part of the specification.
The table below checks what DOM features your browser claims to support. Note that some browsers (such as ICEbrowser) may not accurately declare their capabilities.