SUBNET MASKS
from /0 to /32: the mask, how many addresses a block holds, and how many of them go to hosts
UML DIAGRAMS
the fourteen kinds, and the notation a class diagram is made of
THE UNICODE SPACE
1 114 112 code points in 17 planes: 159 866 characters, 137 468 private, 814 730 free
PERCENT-ENCODING IN URIs
128 ASCII positions: 66 unreserved, 18 delimiters, 43 that must always be encoded — and the "%" itself
THE UTF-8 ENCODING
how a Unicode code point falls into one, two, three or four bytes — and which bytes never appear
UUID
thirty-six characters: where the version sits, where the variant sits, and what each of the eight versions is made of
VIDEO FORMATS
who published each standard, when, the names it goes by, and what has to be squeezed
VIM COMMANDS
modes, motions and editing per the Vim 9.1 help — and the grammar that composes them into commands
NINE DRINKS
the same coffee, different proportions
ARABICA AND ROBUSTA
two species, six varieties, one difference
POST-FERMENTED TEAS
six teas changed by microbes rather than oxygen
ESPRESSO
the nine requirements of a certified Italian espresso, with their tolerances