Requirements for Tibetan Text Layout and Typography

1.1 Purpose of this Document

This document describes requirements for the layout and presentation of text in the Tibetan script for use with Web standards and technologies, such as HTML, CSS, Mobile Web, Digital Publications, and Unicode. In addition to Tibet and China, the script is widely used in Bhutan, Nepal, India and throughout the Tibetan diaspora, and requirements for these regions are also included in the scope of the document.

The document does not describe implementations or issues related to specific technologies, such as CSS. Instead it describes the typographic requirements of Tibetan in a technology-agnostic manner, so that the content remains evergreen and is equally relevant to all technologies that aim to represent Tibetan text on the Web.

In the future other documents or issues may be created by comparing the requirements in this document with the gaps in specific technologies, but that information will be documented elsewhere.

1.2 How this Document was Created

This document uses material from the web page Tibetan script notes and from a talk by Jianxin Yin to establish a base of information that will be developed and refined by discussion, including in the context of China’s National Standards, and by surveying needs from actual users and technical experts.

The following types of experts will be involved in the creation of this document:

1. Tibetan typography experts

2. International and Chinese standardization experts

3. Academic and industry experts

In order to facilitate contributions from the Chinese national standards groups, the text of the document will also be available in Chinese, although the English version remains the authoritative version. It is also expected that some discussions will take place in Chinese or Tibetan, and will then be translated into English during the development of the document.

The technical terms for discussing and describing the Tibetan writing system will be carefully selected after considering potential differences in nuance even if a direct translation exists, and they will be described in both English and Chinese so the discussion can be continued in the future. Also many figures are included to promote understanding for certain parts that are hard to describe.

1.3 Basic Principles for Document Development

This document describes the characteristics of the Tibetan language system along the lines of the following principles.

1. It does not cover every issue of Tibetan typography, but only the important differences from the Western language systems.

2. The technical aspects of actual implementation are not covered by this document.

3. In order to help readers' understanding of how Tibetan is used, typical real life examples are provided.

4. Text layout rules and recommendations for readable design are different matters, but it is hard to discuss these two aspects separately. In this document, these two issues are separated carefully.

2.1 Tibetan Characters 藏文字符

2.2 Consonant Stacking ...

A salient feature of the Tibetan script is the tendency to stack consonant characters belonging to a syllable. A stack has a standard consonant character at the top (although it may actually be slightly squeezed or adapted slightly in shape), and one or more special subjoined consonant characters beneath it.

The word 'head' is often used to refer to either the top-most consonant (ie. spacially) or the root consonant of a syllable, which may be a subjoined consonant. We therefore avoid this term here, and say 'root' or 'topmost'.

The topmost consonant in a stack always uses the standard character from the Unicode Tibetan block regardless of whether it is a root consonant or not, and consonants below it always use a character from the subjoined range.

The example shows a stack with three consonants. (There is also a vowel sign above the stack.)

Unlike Indic scripts, no virama (or halant) is used for Tibetan. Instead, just a full and subjoined form of each consonant. The subjoined forms are combining characters. Avoiding the virama makes sense because the virama is not used by Tibetans, and the approach taken makes it easier to create the large number of stacks contained in Tibetan text.

Subjoined forms of the basic 30 Tibetan consonants are listed below:

The following list shows the order in which characters should be typed, and stored in memory, for a set of stacked characters.

1. Standard consonant shape

2. First subjoined consonant

3. Any other subjoined consonants, in order of descent

4. Subjoined vowel 'a-chung

5. Standard or compound vowel sign, or virama

Some consonant characters are modified using the character U+0F39 TIBETAN MARK TSA-PHRU  ༹  In these cases, the tsa-phru character should be placed in memory immediately after the consonant it modifies.

2.3 Tibetan Syllables 藏文音节

Word boundaries within a section are not indicated, only 'syllables', known as tsheg-bar tsek bar. Syllable boundaries are usually separated by the tsek character, U+0F0B TIBETAN MARK INTER-SYLLABIC TSHEG ་.

The pronunciation of Tibetan words is typically much simpler than the orthography, which involves patterns of consonants. These patterns reduce ambiguity and can affect pronunciation and tone.

The following diagram shows characters in all of the syllabic positions, and lists the characters that can appear in each of the non-root locations. The two-syllable word in the example is འགྲེམས་སྟོན་ 'grems-ston ɖɹem-ton (exhibition).

2.4 Unicode-encoded Tibetan Characters 藏文的字体与字符的Unicode编码

The figure below shows the arrangement of Tibetan characters in the Unicode Tibetan character block, as of Unicode version 8.0.

藏文目前的字形字体为喜马拉雅字体。根据《GB？？？》，藏文字符编码覆盖了Unicode的U+0F00至U+0F0E、U+0F10至U+0F1E、U+0F20至U+0F2E U+0F30+范围。具体如下：

2.5 Tibetan Characters used for Transliteration ...

Many of the characters in the Tibetan block are there for transcribing or transliterating non-Tibetan text. The Tibetan script provides for perfect mappings between Sanskrit and Tibetan, but Tibetan is also used to transliterate other languages, such as Chinese, Mongolian and English.

There are a number of consonants, including a range of aspirated consonants, and the following range of retroflex consonants.

	GHA	DDHA	DHA	BHA	DZHA	KSSA		TTA	TTHA	DDA	NNA	SSA
head
subjoined

The retroflex consonants, which are reversed versions of Tibetan consonant shapes, are often used to distinguish loan words from sequences of Tibetan syllables. For example, ཁ་ཎ་ཌ་ kha-ṇa-ḍa (Canada), མོ་ཊ་ mo-ṭa (car).

In transliterated text consonants are sometimes stacked in ways that are not allowed in native Tibetan text.

There are also additional vowel signs between U+0F71 and U+0F7D for Sanskrit transcriptions, and several are compound shapes. The component parts of these compounds should normally be typed individually, rather than using the compound codepoints. The table below shows the characters, and indicates those whose use is discouraged and strongly discouraged.

II	EE	OO	Rev I	V R	V L	II	UU	Rev II	V RR	V LL
Ok
Discouraged
Deprecated & strongly discouraged

U+0F7F TIBETAN SIGN RNAM BCAD ཿ ( nam chay ) is the visarga, and U+0F7E TIBETAN SIGN RJES SU NGA RO  ཾ ( ngaro ) is the anusvara.

2.6 Tibetan Numerals 藏文的数字

Tibetan has its own set of digits, although publications may also use European numerals. The basic Tibetan numbers are used in the same way as European numerals. They differ only in shape.

藏文有自己的数字表示。藏文数字跟阿拉伯数字本质上没有不同，只是符号表示形式不同而已，但是在藏文中增加了半数字的表示形式。

The Unicode Tibetan block also contains a set of half-numbers. These are very rarely used, and there is some ambiguity about how they are used. By some interpretations, the following shapes each have the value of 0.5 less than the number within which it appears. Used only in some traditional contexts, they appear as the last digit of a multidigit number, eg. ༤༬ represents 42.5.

藏文的半数字是指1到9数字一半的表达方式。例如：1的一半是0.5，2的一半是1，3的一半是1.5等等。在藏文中，可以通过半数字直接表达而不用书写小数树。例如，43.5在藏文中可以直接书写为 ༤༬。

下表是藏文数字（及半数字）与阿拉伯数字表示方法的对应：

2.7 Head Marks 藏文的数字

In traditional, loose-leaf Tibetan pechas a head mark or yig-mgo (yig go) is used at the beginning of the front of the folio so that you can tell which is the front.

Head marks are also used in both pechas and books to indicate the start of a headline or the start of the first paragraph in a longer text.

Head marks differ from text to text. The Unicode Standard provides a number of characters to give some basic coverage, but may not meet all needs.

A common head mark is U+0F04 TIBETAN MARK INITIAL YIG MGO MDUN MA ༄, and there is also the extension character U+0F05 TIBETAN MARK CLOSING YIG MGO SGAB MA ༅. A head mark can be written alone, or can be followed by as many as three closing marks; head marks are also followed by two shads, eg.༄༅། །.

Three less common head marks, used in Nyingmapa and Bonpo literature, are also represented in the Tibetan block, namely:

• U+0F01 TIBETAN MARK GTER YIG MGO TRUNCATED A ༁
• U+0F02 TIBETAN MARK GTER YIG MGO -UM RNAM BCAD MA ༂
• U+0F03 TIBETAN MARK GTER YIG MGO -UM GTER TSHEG MA ༃

2.8 Tibetan Punctuation 藏文的标点符号

3.1 Text Segmentation in Tibetan ...

Key divisions of the text are sections (or expressions (brjod-pa)) and topics (don-tshan), which do not necessarily equate to English phrases, sentences and paragraphs. Sections normally end with a shay, U+0F0D TIBETAN MARK SHAD །, followed by a space. Topics (eg. headlines, verses, and longer paragraphs) are often terminated or separated with shay+space+shay.

A line that ends with the root consonant U+0F40 TIBETAN LETTER KA ཀ or U+0F42 TIBETAN LETTER GA ག will normally swallow up the shay that immediately follows it, even if there is a vowel sign. For example, where you might expect to see a double shay, you might see ཀུ ། and སྐུ །. However, the shad is not omitted if these characters have a subscript, eg. གྲུ། །.

Word boundaries within a section are not indicated. Only 'syllables', known as tsheg-bar tsek bar, are separated by the tsek character, U+0F0B TIBETAN MARK INTER-SYLLABIC TSHEG ་.

The tsek is not used before a shay, except after U+0F44 TIBETAN LETTER NGA ང. For example, note the end of the three sections in this example:

Users may use an ordinary TSHEG between NGA and SHAD, but Unicode also provides a special non-breaking character that can be used instead, U+0F0C TIBETAN MARK DELIMITER TSHEG BSTAR ༌. The word 'delimiter' in the name is a misnomer.

Whitespace in Tibetan text should use U+00A0 NO-BREAK SPACE. Spaces in Tibetan text are usually wider than spaces in English text, and typically only occur after one of the following: །, ༑, ༔ or ཿ. However, numbers and embedded Western text are surrounded by smaller spaces, eg. ལོ་ ༢༠༠༡ ཤིང་བྱ་ཟླ་ ༩ ཚེས་ ༥ ཉིན་.

3.2 Text Emphasis and Highlighting ...

U+0F35 TIBETAN MARK NGAS BZUNG NYI ZLA  ༵ and U+0F37 TIBETAN MARK NGAS BZUNG SGOR RTAGS  ༷ can be used to create a similar effect to underlining or to mark emphasis.

These marks attach to a syllable rather than a character and therefore to place them correctly it is necessary to take syllable boundary positions into account. If entered as combining characters they can be added after the vowel-sign in a stack.

Application software has to ignore these characters for text processing operations such as search and collation.

Alternative methods of emphasis include use of a different colour, or the use of the prefix ༸.

These characters may also be used in interspersed commentaries to tag the root text that is being commented on. An alternative is to set the tsek-bar being commented on in large type and the commentary in small type.

Modern texts tend to bold text for emphasis.

3.3 Baseline alignment ...

When text in smaller annotations or larger heading text is mixed with normal text, the letter-heads of all characters should align to the same height.

4.1 Tibetan Writing Mode 藏文的书写方式

Tibetan is written horizontally and read from left to right.

藏文文字为“从左至右”书写、“从上向下”显示，也简称为横排从左至右排版。

4.2 Line breaking ...

Normally, Tibetan only breaks after a tsek (U+0F0B TIBETAN MARK INTER-SYLLABIC TSHEG ་), and doesn't break after spaces.

Line breaks do not occur after a tsek when it follows U+0F44 TIBETAN LETTER NGA ང (with or without a vowel sign) and precedes a shay (U+0F0D TIBETAN MARK SHAD །).

If the character after NGA is an ordinary tsek, then lines should not break between the tsek and the shay. Text is likely to be more portable if content authors use the TSHEG BSTAR in these locations, instead of the normal tsek.

Line breaks are also possible after:

• U+0F0D TIBETAN MARK SHAD ། - as long as the next line starts with a consonant (ie. not a second shad).

• U+0F14 TIBETAN MARK GTER TSHEG ༔

• U+0F7F TIBETAN SIGN RNAM BCAD ཿ (used to represent the visarga in transliterations). There is never a tsek after this character, eg. ཨོཾ་ཨཱཿཧཱུྃ་.

Tibetan never breaks inside a syllable, and has no hyphenation. If a word is composed of multiple syllables, it is also preferable to avoid breaking a line in the middle of the word.

A line must never start with a shad.

4.3 Justification ...

There are two alternative methods of justification.

4.3.2 Tsek padding ...

While hand writing, authors add small spaces across the text to get the line end as near as possible to the right margin. Where space remains at the margin, it may be left as is, if it is short. Otherwise, the remaining space will be filled with tseks to make the line as flush as possible with the right margin (there will usually still be a slight raggedness to the right edge of the text).

There are a couple of detailed rules about the use of tsek padding.

Justifying tseks are almost always used when the line ends in a tsek. If, however, the line ends in a shay, there are a number of alternatives.

If the line ends with a single shay the shay is followed by spaces. Tsek padding is never applied after spaces. (See examples in the figure above.)

If the line ends in a double shay (with space between), it is unusual (though possible) to add tsek padding. Instead, the space between the shays is stretched or narrowed. (See examples in the figure below.) The same applies if the second shay was removed because it was preceded by a KA or GA.

4.4 Lists and counters ...

Tibetan numerals can be used for list counters. The Tibetan numbers are used in a simple decimal notation, ie. in the same way as European numerals. They differ only in shape.

European numerals can be used for list counters. The European numeral is followed by a period.