.empty and .length Amend language manual?

[dcoder]

I'm using the language reference on dlang.org (which is awesome), 
anyways, I can't find a description of .empty in the array 
section. Should it be there?  I don't see it in the property 
section either.

Could someone more expert than me, add it in somewhere?  Thanks.
Also, is there any surprises / difference between the two:

if( !arr.length)

and

if( arr.empty)

do they produce the same thing all the time?

thanks.