Need help with storage class definition

[mist]

While working on 
https://github.com/D-Programming-Language/phobos/pull/863 I have 
noticed that inout breaks ParameterStorageClassTuple and family. 
I have started working on a fix but quick comparison of 
http://dlang.org/declaration.html#StorageClass vs 
http://dlang.org/phobos/std_traits.html#.ParameterStorageClassTuple 
have left me in confusion without clear understanding what 
parameter storage classes are supposed to be defined to.

There is also InOutX entry in grammar which lists some of storage 
classes and seems more relevant to parameter storage classes 
(i.e. includes ref).

Can someone give a more structured explanation: what is supposed 
to be a storage class, what is supposed to be a type storage 
class and what - a type qualifier? I'd like to update std.traits 
demanglers to the latest state of things, but grammar description 
does not seem clear enough.