In HTML, what do the <ol> attributes start, reversed and type do, and what does the value attribute on an <li> change?

## Why ordinals are markup, not decoration An `<ol>` differs from a `<ul>` in exactly one way that matters: the order of its items is part of the meaning. Steps in a recipe, finishing positions in a race, and chapters of a document are ordered lists; a set of tags or navigation links is not. Because the order carries meaning, HTML gives you attributes to control the *numbers themselves*, not just how they look. ## start `start` takes a valid integer and sets the ordinal of the first item. ```html <ol start="4"> <li>Rinse the beans</li> <!-- 4 --> <li>Grind coarsely</li> <!-- 5 --> </ol> ``` The classic use is a list interrupted by explanatory prose: you close the first `<ol>` after step 3, write a paragraph, then open `<ol start="4">`. The alternative — typing "4." into the item text — produces a number that is content rather than structure, so it survives copy-paste but breaks the moment a step is inserted, and it doubles up with the marker the browser already draws. `start` is reflected by the DOM property `HTMLOListElement.start`. ## reversed `reversed` is a boolean attribute: present means the list counts down. ```html <ol reversed> <li>Third place</li> <!-- 3 --> <li>Second place</li> <!-- 2 --> <li>Winner</li> <!-- 1 --> </ol> ``` With no `start`, the first item's number equals the number of items in the list, so a three-item reversed list runs 3, 2, 1 — the countdown you want for a top-N list written worst-first. Add `start` and the first item takes that value instead, so `<ol reversed start="10">` runs 10, 9, 8… That combination is how a "top 10" list rendered in ascending drama order gets its numbers right without any scripting. ## type `type` chooses the marker series and takes one of five values: `1` (decimal, the default), `a` (lowercase latin letters), `A` (uppercase latin), `i` (lowercase roman numerals), `I` (uppercase roman). `<ol type="A">` produces A, B, C. The attribute is valid on `<ol>`. It is *not* valid on `<ul>` or on `<li>` — the old `type` attribute on those elements is obsolete, and bullet shape is a styling concern. Use `type` on `<ol>` when the numbering style is part of the content's meaning (a legal document whose clauses are cited as "clause (iv)"), and leave purely decorative marker choices to the stylesheet. ## value on <li> `value` takes an integer and sets that specific item's ordinal. Crucially, the items after it continue from the new number rather than resuming the old sequence: ```html <ol> <li>One</li> <!-- 1 --> <li value="10">Ten</li> <!-- 10 --> <li>Eleven</li> <!-- 11 --> </ol> ``` That makes it the tool for a list with a deliberate gap — showing steps 1, 2, then jumping to 7 in an abridged tutorial, or reproducing a numbered source document faithfully. `value` has no effect on an `<li>` whose parent is a `<ul>`; it is reflected as `HTMLLIElement.value`. ## What this is not Two boundaries are worth stating in an interview. First, these attributes control the *ordinal*, and the marker glyph you see is drawn by the browser from that ordinal — how the marker is styled belongs to CSS, and a stylesheet can suppress markers entirely without changing the ordinals in the DOM. Second, none of this is a reason to hand-write numbers into item text. Markup-driven ordinals renumber automatically when items are inserted, removed, or reordered by a template, which is precisely the class of bug hand-typed numbers create. ## Choosing between them in practice Reach for `start` when a single list is split by other content; `reversed` when the semantic order is descending; `value` when one item's number is an exception rather than the whole sequence; and `type` only when the numbering style itself is meaningful. If you find yourself using `value` on most items, the list is probably not really an ordered list — or the data, not the markup, should be producing the sequence.