...It literally isn't! In that list, I mean.
The old No. 80 set (first appeared in the Mastersound Flatwound line in 1959) did have almost identical gauges, though.
The Ernie Ball String Gauge Guide, originally scanned and shared by
@rick harper (
besides stainless) and then enthusiastically spammed here and there by
in this invaluable post of
both, is from 1977.
@JTE's post
is about Fender Studio Bass roundwounds and flatwounds coming stock on Fender bass models, in or around 1983.
However, at one point (
June 1979 at the latest),
the 980M Studio Bass flats were
Fender "Studio Bass" Strings. At least in the Sixties, the earlier No. 80/ No. 850 sets (at least in the Sixties) had been round-core, like basically all the competition back then.
Less expectedly, even the latest Mexican-made 9050 sets, right until their discontinuance in 2008, were still round-core (
*nickel* (unlike Gianni's specific set), as well as hex-core) according to @hasbeen, who designed the following (2010-), hex-core versions.