Direction
Computers were originally designed to use left-to-right (LTR) scripts. Examples of LTR scripts include Roman, Cyrillic, Ethiopic, and Indic scripts. There are also absolute right-to-left (RTL) scripts (some instances of Hebrew), mixed RTL (Arabic, Syriac, Thaana), top-to-bottom-RTL (Chinese and Japanese are examples of these), and top-to-bottom-LTR (Mongolian). These are the most common types in use today. There are, of course, other possibilities, such as boustrophedon. When typesetting historic texts, being able to handle this system may also be necessary, but is rarely required.
| Setting | Full Name | Description | Examples |
|---|---|---|---|
| LTR | Left-to-right (horizontal) | A script in which text is written in horizontal lines, with each line beginning at the left and going towards the right. The first line tends to be at the top of the page. | Buhid Greek Osmanya |
| RTL | Right-to-left (horizontal) | A script in which text is written in horizontal lines, with each line beginning at the right and going towards the left. The first line tends to be at the top of the page. | Phoenician |
| RTL bidirectional | Right-to-left (bidirectional) | A script which is written predominantly from right to left, but which contains some exceptions written from left to right. These exceptions are commonly numbers, and brand names which originated in a left-to-right script. | Arabic Thaana |
| Vertical (LTR) | Vertical (left-to-right) | These scripts are written in vertical columns, with the first column on the left and the final column on the right. Columns are normally, but not invariably, written from top to bottom. | Hanunóo Mongolian |
| Vertical (LTR) and horizontal (LTR) | Vertical (left-to-right) and horizontal (left-to-right) | These scripts can be written either vertically or horizontally. When written in vertical columns, the first column is on the left and the final column is on the right. When written horizontally each line begins at the left and proceeds towards the right. | SignWriting |
| Vertical (LTR) and horizontal (RTL) | Vertical (left-to-right) and horizontal (right-to-left) | These scripts can be written either vertically or horizontally. It is often, but not always, the case that they were traditionally written vertically but have come to be written horizontally in printed text for ease of typesetting. When written in vertical columns, the first column is on the left and the final column is on the right. When written horizontally each line begins at the right and proceeds towards the left. | Sogdian |
| Vertical (RTL) | Vertical (right-to-left) | These scripts are written in vertical columns, with the first column on the right, and the final column on the left. It is more common for vertical scripts to be written this way than from left to right. Columns tend to be written from top to bottom. | Phags-pa Meroitic Hieroglyphs |
| Vertical (RTL) and horizontal (LTR) | Vertical (right-to-left) and horizontal (left-to-right) | These scripts can be written either vertically or horizontally. Often, they were traditionally written vertically but have come to be written horizontally in printed text for ease of typesetting. When written in vertical columns, the first column is on the right and the final column is on the left. When written horizontally each line begins at the left and proceeds towards the right. | Japanese Han |
| Boustrophedon | Boustrophedon | A script in which alternate lines are reversed. Every other line must be read in the opposite direction to the preceding line, and in addition to this, individual letters on alternate lines are reversed. Some boustrophedon scripts are written with alternate lines being rotated 180°, that is, flipped ‘upside-down’, as well as being reversed. | Rongorongo LinearB |
| Other | Other | Some scripts can be written in a number of directions. Others are not written in clear rows or columns; they may be more pictoral in the way they are arranged. | Ogham |
Portions of this content first appeared in Implementing Writing Systems, copyright © 2001 SIL International.