Technik für den elektronischen Markt

"Sprachen des EM: SGML und HTML"

4. Dezember 1996

A Short SGML Glossary

application:

see SGML application.

attribute:

named value associated with a specific occurrence of an element.

attribute list declaration:

a formal markup declaration beginning with the keyword ATTLIST that associates an element with one or more attribute definitions. An attribute definition contains an attribute name, a declared value and a default value.

comments:

are information to be ignored by an SGML parser. This means comments may be used to put explanatory notes in a DTD or to pass messages in a document among its authors and editors.

content:

within a document, is one level of information (the other level is information about the content, markup of some kind). In SGML, information content is made up of data characters and is enclosed within markup.

content model:

In element declarations, element types are defined using content models. Content models contain one model group which in turn can contain subelements or a keyword indicating allowed character data.

data characters:

letters of the alphabet, numbers,punctuation, and the special symbols specified in the SGML declaration.

declarations:

describe the logical structures within related or similar documents (classes od documents).

declaration subset:

contains within delimiters (or delimiter characters) (typically [ and ]) the element, attribute, entry, notation, short reference and usemap declarations that establish the markup for the document. (Also called "document type declaration subset".)

delimiter characters:

(also called delimiters) are normal characters which are assigned special roles in SGML to allow humans and computers to easily distinguish markup and content.

document instance:

what we traditionally have thought of as the document itself, the actual content mixed in with the actual markup; can be a single document or part of a document instance set that follows the DTD.

document type declaration:

a formal declaration that begins with the keyword DOCTYPE, followed by the name of the base element (also called the top or containing element) of that document, followed by the declaration subset which tells a system exactly what markup to expect.

document type definition (DTD):

In common usage, DTD has come to stand for the formal constructs that appear in a declaration subset. Officially, the document type definition also includes informal guidelines or conventions that makeup an SGML application.

element declaration:

a formal markup declaration beginning with the keyword ELEMENT naming the element type and defining its required and allowed content in a content model.

element type:

the first parameter in the element declaration, names the logical object(s) whose content will be defined in the content model. The name defined in the DTD becomes the generic identifier or tag name of the element when it is marked up in the document instance.

entity:

"a collection of characters that can be referenced as a unit" (ISO 8879:1986). Entities provide a useful way of easily incorporating often repeated characters, phrases or paragraphs within a document; or bringing separate units of information (graphics or external files, for example) that are stored externally into an SGML document at the time of processing.

entity declaration:

a formal markup declaration beginning with the keyword ENTITY. It names an entity and defines the content which it can replace. There are two types of entity declarations:general entities establish substitutions which appear in the document instance; and parameter entities define substitutions that occur within the DTD.

markup:

In a document, if content is one level of information, markup is a second level, providing information about the content. In SGML documents, markup is composed of markup characters.

markup characters:

contain letters, numbers, and punctuation characters that are mixed with data characters but made distinct from data characters (content) by delimiter characters.

notation:

When content is not made up of standard data characters, the use of notations allows documents to incorporate or reference non-SGML data (such as graphics, video, sound, or small software applications).

notation declaration:

a formal markup declaration beginning with the keyword NOTATION. It names a notation and indicates to the processing system how to process that content.

parser (conforming or validating SGML parser):

a computer program that either reads or assumes an SGML declaration, then reads the DTD to learn application-specific rules of markup, and then determines (and perhaps reports) if the document instance conforms.

SGML application:

the formal constructs (markup declarations), the informal guidelines (comments, processing instructions, and documentation) or conventions that are used to apply SGML to a set of documents.(HTML 2.0, for example, is an SGML application.)

SGML declaration:

a formal, standardized set of keywords that tell a receiving system which character set, delimiters and optional SGML features are being used.

SGML document:

a sequential collection of data and markup characters organized to begin with an optional SGML declaration, followed by a document type definition, followed by the document instance conforming to the DTD.