31. IEC 80000-13 — Information science and technology
The tenth and last part specified is IEC 80000-13, Information science and technology —
the second IEC-published part, after electromagnetism. Every item — all of 13-1 … 13-42,
forty-two in all (the part uses flat item numbers, no sub-suffixes) — is catalogued: the
teletraffic quantities, storage and transfer, the powers and signal energy, and the
coding- and information-theory quantities — each carrying its exact source as data. Only
citation locators are recorded; no normative content from the licensed standard is
reproduced. The defining mathematics of selected remarks is specified in the sibling
module Part13.DefiningRelations.
Information science is where the scale-spanning reduction (the Scale-spanning units chapter, requirement R13) meets human-selected counts of information. Its characteristic quantities are all dimension one — and yet they carry special, mutually incommensurable units, and belong to distinct kinds. Information content and entropy are measured in the shannon (or hartley, or natural unit); traffic intensity in the erlang; storage capacity in the bit. All are dimension one; the dimension functor collapses them to a single point, and only the kind keeps the shannon of information from the erlang of traffic from the bit of storage. The shannon, erlang, and bit are scale-spanning units in exactly the sense of the candela and the mole: dimensionless references chosen by people.