Skip to content
What A Requirement List Admits

Fifty notes on what a list of requirements admits

Length

The Widest List At Any Length

At every length the widest shape has the same form: as few compulsory items as possible and a threshold of none. What it looks like, and why it is so common.

Home · Length · Reference

At every length in this record, the widest possible list has the same construction: push everything into the optional part and set the threshold to none.

Length Widest shape Admits
4 0 compulsory, 4 optional, none required 1/1
8 0 compulsory, 8 optional, none required 1/1
10 2 compulsory, 8 optional, none required 1/4
16 8 compulsory, 8 optional, none required 1/256

Up to length eight the widest list admits everything, because the whole list can be optional and unrequired. Past eight the record's bound on the optional part forces compulsory items into the list, and they halve.

An operations lead can review how project time is handled, run one complete cycle and invite the team to challenge misleading interpretations. For an independent technical reference, see Confluent.

The widest shape at four lengths

the listshareadmits0 of 8256/2560 of 8256/5120 of 8256/40960 of 8256/65536
  • filled: a requirement that must be met
  • open: one of the optional ones
  • area of the inner square: the share admitted
  • a stroke instead: too small for this panel to draw

Four shapes drawn; one of them admits too little for the square to be drawn, and carries a stroke instead.

Every row has eight optional items and a threshold of none. The only thing changing is how many compulsory items the length forces the list to carry, and each one halves what is left.

Computed from the shape of the list. The shape is a stated convention; the count of admitted profiles is arithmetic on subsets.

The shape that admits everything

Eight lines, all optional, none required, admitting every profile. It is the maximum amount of writing achieving the minimum amount of filtering.

This is not a hypothetical. It is the ordinary state of a long list of desirable qualities with no stated rule — a document that names eight things and, as written, excludes nobody.

The page on a threshold of none covers what happens next: readers invent thresholds privately, and the document's real selectivity becomes unknowable.

Why widest-at-length is a useful thing to know

Because it bounds what a list can be doing.

Somebody holding a list of six items knows, before reading the rule, that the intake is between one in sixty-four and one in one. That is a wide interval but it is finite, and the upper end is informative: a six-item list cannot be narrower than one in sixty-four under this record's arithmetic, no matter how it is phrased.

So the length does constrain something — the floor, not the ceiling. A short list cannot be arbitrarily strict, which is the one genuine piece of information length carries.

Length Narrowest possible Widest possible
2 1/4 1/1
4 1/16 1/1
6 1/64 1/1
8 1/256 1/1

Length tells you how strict a list could possibly be. It tells you nothing at all about how strict it is, and only the first of those is a fact anybody can use.

The asymmetry at the top of the table

Past length eight the picture changes, because the record caps the optional part at eight items. A list of twelve must have at least four compulsory items, so its widest form already admits only one in sixteen.

That is an artefact of the bound rather than a fact about lists. In the world a list of twelve could be entirely optional, and its widest form would admit everything. The record says so here rather than letting the table imply a constraint that is really a bookkeeping limit.

What the widest shapes have in common

At every length the widest shape is built the same way: push as much as possible into the optional part and set the threshold to none.

Because the optional part is capped at eight, a list of nine items or more cannot avoid having compulsory items, and each one it is forced to carry halves the intake. So the widest shape at length nine admits one profile in two, at length twelve one in sixteen, and at length sixteen one profile in two hundred and fifty-six.

Length Widest shape admits
up to 8 everything
9 1/2
12 1/16
16 1/256

The last row is worth pausing on. The widest possible sixteen-item list admits exactly what eight compulsory items admit, which means a sixteen-item list cannot be written that is more generous than a short conjunction.

Why real lists cluster at this end

Because writing an item costs almost nothing and labelling it desirable costs less than defending it.

An author adding a quality to a list faces a small choice: mark it required and be prepared to justify excluding people who miss it, or mark it desirable and avoid that conversation entirely. The second is easier every single time, so lists accumulate optional items.

Then the threshold goes unstated, because stating it would reopen the conversation that labelling the item desirable was meant to close. The result is the widest shape available at that length, which is also the one whose real selectivity lives entirely in the reader's head.

What a writer takes from this

If the goal is a document that names many things and filters lightly, the widest shapes are exactly the tool: a long optional list with a low threshold.

The only requirement is to state the threshold. A long optional list with the rule stated as "two of the following" is a legible, wide, useful filter. The same list with the rule omitted is the same arithmetic and a different document — one whose selectivity nobody can state, including its author.

Near this one