Special Characters

This section contains information of how user agents should treat control characters and other special characters.

Character Data

The characters between the tags represent text encoded according to ISO 8859/1 8-bit single-byte coded graphic character set known as Latin Alphabet No. 1, or simply Latin-1. There are 256 character positions in the Latin-1 encoding. Latin-1 includes characters from most Western European languages. It consists of the space character, 186 characters that form a subset of the graphic characters in ISO 6937/2 (1983), and four additional characters that are intended for inclusion in ISO 6937/2. For more information, see Character Sets

The lower 128 character positions include a space, 33 control characters, the 26 upper- and lowercase letters of the english alphabet, 10 numerals and 32 other printing characters This subset, functionally identical to ASCII, is defined by ISO 646 7-bit coded character set for information interchange, also known as the International Reference Version. ISO 646 is identical in most respect to the ANSI standard for ASCII (American Standard Code for Information Interchange). The only significant difference between ISO 646 and ASCII is the specific names assigned to the control characters which occupy positions 00-31 and 127

The upper 128 positions include a non-breaking space, a soft hyphen indicator, 93 graphical characters, 8 unassigned characters, and 25 control characters. The non-breaking space and soft hyphen indicator are not recognized and interpreted by all HTML browsers, and their use is discouraged

There are 58 character positions which are occupied by control characters. See the discussion for details on the interpretation of control characters. Because certain special characters are subject to interpretation and special processing, information providers and browser implementors should follow these guidelines

Certain characters may not be accessible from your keyboard, or some part of your system (i.e. translation software) may not be equipped to deal with 8-bit character codes. HTML and many WWW browsers provide character entity references and numerical character references to facilitate the entry and interpretation of characters by name and by numerical position.

Because certain characters will be interpreted as markup, they should be"escaped"; that is, represented by markup -- numeric character or entity references.

Special Characters

Certain characters are taken to have special meaning within the context of an HTML document. There are two printing characters which may be interpreted by the browser to have an effect of the format of the text:

Space

• Interpreted as a word space in all contexts except <PRE>.
• Interpreted as a no-break space within <PRE>.

The character entities &ensp; and &emsp; denote an en space and an em space respectively, where an en space is half the point size and an em space is equal to the point size of the current font. For fixed pitch fonts, the user agent can treat the en space as being equivalent to a single space character, and the em space as being equuivalent to two space characters.

Non-breaking Space (&nbsp;)

Hyphen

• Interpreted as a hyphen glyph in all contexts.
• Interpreted as a potential word space by hyphenation engine.

The character entities &endash; and &emdash; denote dash marks with the same widths as the &ensp; and &emsp; entities respectively.

Control Characters

Control characters are non-printable characters that are typically used for communication and device control, as format effectors, and as information separators.

In SGML applications, the use of control characters is limited in order to maximize the chance of sucessful interchange over heterogenous networks and operating systems. In HTML, there are only three control characters which are used. The remaining 55 control characters are shunned and should not appear in an HTML document. The valid control characters and their interpretation are:

Horizontal Tab (HT - 9 dec)

• Interpreted as a word space in all contexts except <PRE>.
• Within <PRE>, the tab should be interpreted to shift the horizontal column position to the next position which is a multiple of 8 on the same line; that is, col := (col+8) mod 8.

Line Feed (LF - 10 dec)

• Interpreted as a word space in all contexts except <PRE>.
• Within <PRE>, the tab should be interpreted as a shift to the start of a new line; that is, col := 0; row := row+1

Carriage Return (CR - 13 dec)

• Interpreted as a word space in all contexts except <PRE>.

• Within <PRE>, the tab should be interpreted as a shift to the start of the line; that is, col := 0;

Numeric Character References

Any printing character within the 8-bit character encoding of ISO 8859/1 (256 character positions) or the 7-bit character encoding of ISO 646 (128 character positions) may be represented within the text of an HTML document by a numeric character reference, e.g. &#233; is a small e with an acute accent. It is recommended that character entity references such as &eacute; are used in preference to numberic character references.