2.1 section tells:
> By default, the sessionId is null. The only time the null value is a valid sessionId is before a call to newSession.

But actually "sessionId" is defined as non-nullable:
attribute DOMString sessionId;

I would expect it to be defined nullable:
attribute DOMString? sessionId;

Also 2.2 section tells:
> unless the command's sessionId was the null value, in which case a unique sessionId must be assigned (see newSession for how this is achieved).

That means that if a local end sends a command with name "invalidName" a remote end should instantiate a new session and return its id. IMHO the only command that should involve instantiation of new session should be "newSession", not an arbitrary command with "sessionId" set to null. 


Also 2.1 section tells:
> The name of the command to execute is held in the name, and this must be handled case-sensitively. It defaults to the null value.

But I don't understand why it should default to any value. It seems that name with null value is a nonsense.


Also section 2.2 says that "value" is nullable. But it's not marked as such in IDL definition.