 Visual text order

Visual text order is the ordering of displayed text items within a rendered line. In bidirectional text it can differ from logical text order, the stored character sequence. It describes a presentation result, so the line boundaries and resolved directional information belong to its context.^[ref]

For an original permutation example, take six logical items $a,R_1,1,2,R_2,b$ with supplied levels $0,1,2,2,1,0$. The resulting left-to-right display positions contain source indicesThus the displayed items are $a,R_2,1,2,R_1,b$. The digits keep their internal order even though the surrounding right-to-left items exchange physical positions. A single reversal of the whole stored list would give a different result.

A position map preserves information that a picture alone may lose. If two source items both display as the same letter, their appearances do not reveal which logical index each came from. A renderer can retain distinct indices while drawing identical shapes. Likewise, interpreting a pointer position as a text location requires more information than simply treating a visual column number as a logical index.

The Unicode Bidirectional Algorithm orders text items, while text shaping determines additional glyph forms and combinations. Distinguishing these stages prevents a permutation of character positions from being mistaken for a complete specification of glyph geometry.^[ref]

Visual order is therefore useful for describing what appears on a particular line, while logical text order supplies stable positions for the represented sequence. Reporting both orders and their mapping makes an example reproducible without assuming that the reader's own browser will display a mixed-direction string in the intended way.