Glossary

Each word below links to the section that defines it, in the protocol or the SDK design.

• area: a rectangle of cells, given as c, r, w and h. It is where an element is, in an event (§9), or where a finger drags in the cells (§9.6).
• capability: a field of the host's answer to the query, such as its version, its cell size or its features (§4).
• cell: one character's place in the terminal's grid. A placement's size and position are counted in cells (§5.3).
• delta: a change to a surface's document, a list of ops applied as one (§6.1).
• document: the HTML a program sends for a surface, with a=doc (§5.1).
• event: what the host reports of the user, written to the program's input as a=ev (§9).
• feature: something optional a host has, listed in its capabilities: passthrough, hover, count or menu (§4).
• host: what draws a program's surfaces: usually the terminal itself, sometimes a polyfill or a multiplexer (§2).
• keymap: the keys an element binds to actions, from the data-keys of it and the elements around it (§10.2).
• morph: changing an element into new HTML while keeping what the user was doing in it (§6.2).
• op: one change in a delta, such as text, attr or morph, on an element found by its id (§6.1).
• placement: the rectangle of cells that shows a surface, made with a=place (§5.2).
• prefix: a key bound to prefix, which sends the program itself and every key after it, until the program gives them back with a=focus or a=blur, the surface loses the keyboard, or the user focuses an element of it with a press (§10.5).
• program: the process whose output the terminal shows; it holds the state and decides what each event means (§2).
• rendition: one of the three ways a program shows itself: surfaces, cells or plain data (SDK design §2.5).
• resource: named bytes with a MIME type, such as an image, sent with a=res and referred to as cid:<id> (§7.1).
• surface: a named HTML document, and at most one placement showing it (§5).
• window: the part of a surface that its placement shows, chosen with x, y, w and h (§5.2).

How hotty works shows most of these in one round trip.