The following sentence appears in the rationale:

    The backing store of a fixed-array, which may be a heterogeneous
    or homogeneous vector, is created, accessed, etc., via the
    components of objects we call array-manipulators.

But each such object is called an "array-manipulators", which means
that we need to say "array-manipulatorses" (or more grammatically
"array-manipulator objects") when referring to more than one of them.
For this reason, I think it's important to have a singular name.  We do
not refer to a list or a vector as "an elements".

If you think "type" or "class" is too overloaded, we could use "interface",
which is not currently used in Scheme for anything, and speak of a
backing-store-interface.

--
John Cowan          http://www.ccil.org/~cowan        xxxxxx@ccil.org
First known example of political correctness: After Nurhachi had united
all the other Jurchen tribes under the leadership of the Manchus, his
successor Abahai (1592-1643) issued an order that the name Jurchen should
be banned, and from then on, they were all to be called Manchus.
                --S. Robert Ramsey, The Languages of China