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re: It [density] can also be deduced from the definitions of array-total-size 
    and array-row-major-index, because the range of array-row-major-index's
    answer is defined to be a range of integers that contains just enough
    members to supply a value for each subscript set, with no gaps.
I think my previous note mentioned that density in storage isn't actually
required by this bijective mapping -- it would only do so if the output
of array-row-major-index were required to be a memory index.

Perhaps one couldn't imagine any other meaning for array-row-major-index
other than "index offset from base memory location"; but CLtL doesn't
say this now, and I can certainly think of alternative representations
which would reinject the "linearized" index into the multi-dimensional
format simply in order to preserve the documented property.

If any clarification is necessary, then it ought to take into account
the AREF-1D proposal, which would raise some efficiency questions if the 
bijective mapping weren't "index-offset" memory access.

-- JonL --