Chapter 6Text and Multimedia Languages and Properties..

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Introduction Document has given syntax and structure

also has semantics may have presentation style associated

with it Figure 6.1 depicts all these relationships document can also have information

about itself, called metadata

Syntax of document can express different elements such as structure, presentation style, semantics

one or more of these elements may be given together structural element (e.g. section) can have

fixed formatting style

Syntax of document can be implicit in its content expressed in declarative language or PL

current trend is to use languages that provide information on document

structure format semantics

readable by humans and computers SGML is one such language

Metadata Metadata is data about data metadata associated with text include

author date of publication source of publication document length (in pages, words, bytes) document genre (book, article, memo)

Machine Readable Cataloging Record (MARC) is most used format for library records

In Web, metadata used for many purposes cataloging content rating (e.g. to protect children

from reading some type of document) intellectual property rights digital signatures (for authentication) privacy levels (who should/should not

have access to document) application to EC, etc.

New standard for Web metadata is Resource Description Framework (RDF)

RDF allows description of Web resources

consists of description of nodes and attached attribute/value pairs nodes can be any Web resource (any URI),

that include URL attributes are properties of nodes, and their

values are text strings or other nodes

Text With the advent of computers,

necessary to code text in binary digits

first coding schemes were EBCDIC and ASCII

for internationalization of oriental languages like Chinese or Japanese Kanji, 16-bit Unicode (ISO10616) exists

Text Formats No single format for text document in the past, IR systems would convert

document to internal format cannot change content of document

current IR systems have filters to handle most popular documents, in particular Word, WordPerfect or Framemaker

Other text formats for document interchange Rich Text Format (RTF)

used by word processors and has ASCII syntax

Portable Document Format (PDF) developed for displaying and printing

documents Multipurpose Internet Mail Exchange

(MIME) used to encode electronic mail