Chapter 6 Text and Multimedia Languages and Properties

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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

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• 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

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• 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

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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

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• 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.

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• 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

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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

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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

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• 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

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