CONSTELLATIONS BY SEASON
the northern evening sky through the year: 28 constellations per the Yale Bright Star Catalogue, latitude 40° N, evenings near 9 pm
METEOR SHOWERS
the twelve principal showers of the year · periods, peaks and ZHR per the IMO calendar
SPRING AND NEAP TIDES
the Earth–moon–sun geometry that makes the tides swing — after NOAA
BLOOD PRESSURE CATEGORIES
the six AHA categories · 2025 guideline · the higher of the two readings decides
CPR AND CHOKING
the 2025 American Heart Association algorithms, step by step — bystander, trained rescuer, and choking at three ages
DRESS CODES
six lines that turn up on an invitation, and what each one actually asks for — after Debrett’s
THE CHILD IMMUNIZATION SCHEDULE
Table 1 of the CDC schedule, by age: all twenty rows from birth to 18 years, United States, 2025
MAGNESIUM COMPOUNDS
the share of magnesium in the salt, computed from the formula · and what human trials measured
NAIL SHAPES
eight shapes at one scale · what tells them apart in millimetres
SERUM ACTIVES
when to apply, what to keep apart in time, what the season changes
THE STAGES OF SLEEP
light, deep and REM as honest shares of the night — and the 90–110 minute cycles it is built from
CSS GRID
the container properties and the item properties per the css-grid-2 specification — and what each does to the layout
BITS, BYTES, KILOBYTES
two scales · 1000 and 1024 · why a drive looks smaller
THE DMX512 PROTOCOL
512 channels down one serial wire, and why a full universe cannot refresh faster than 44 times a second
EAN-13
how thirteen digits become 95 modules of bars and spaces
FILE DESCRIPTORS
Three levels between a number and a file: what two numbers of one description share, what two descriptions do not — and where the offset lives
FILE LOCKS
A lock lies on a range of bytes, it has two different kinds of owner, and it guards no byte at all
FILE PERMISSIONS
Nine bits in three triads, three special bits — and why r and x on a directory are different powers
CSS FLEXBOX
main axis and cross axis · which property belongs to which
FLOWCHART SYMBOLS
10 shapes, and one algorithm drawn with them
![FILENAME EXPANSION: *, ?, […]](/api/img/cmsp2eg3h001q2dpdnyxkt8mu)
FILENAME EXPANSION: *, ?, […]
A leading dot and a slash disappear only in filename expansion: the same pattern “*” is seen by case, but not by expansion itself
GO vs RUST
seven questions, the same to both, and the document each answer is written in
HERE-DOCUMENTS
The body reaches the command as a single word, and one quote in the delimiter decides whether it arrives as typed
HTTP STATUS CODES
five classes · twenty codes you meet every day