make-typed-aref-vector

Greetings Lispers!

In the docs for system:make-typed-aref-vector it is stated:

"Makes a vector that can be accessed efficiently.
make-typed-aref-vector byte-length => vector"

And for typed-aref:

"Accesses a typed aref vector efficiently.
typed-aref type vector byte-index => value"


Question: what are byte-length and byte-index? For example, if I want a typed vector of the type (unsigned-byte 32) and the length of 10 should I specify byte-length as 40 (10 elements * 4 bytes for the type unsigned-byte 32) or just as 10? What if I want a typed vector of floats, bytes? What values should I provide for byte-length and byte-index in those cases?


Best,
 Art