• Chapter 1: Getting Started with Stylus Studio®
• Chapter 2: Editing and Querying XML
• Chapter 3: Converting Non-XML Files to XML
• Chapter 4: Working with XSLT
• Chapter 5: Creating XSLT Using the XSLT Mapper
• Chapter 6: Debugging Stylesheets
• Chapter 7: Defining XML Schemas
• Chapter 8: Defining Document Type Definitions
  • What Is a DTD?
  • Creating DTDs
  • About Editing DTDs
  • About Modifiers in Element Definitions in DTDs
  • Defining Elements in DTDs
  • Defining General Entities and Parameter Entities in DTDs
    • Steps for Defining Entities in DTDs
    • General Entity Example in a DTD
    • Parameter Entity Example in a DTD
  • Inserting White Space in DTDs
  • Adding Comments to DTDs
  • About Node Properties in DTDs
  • Associating an XML Document with an External DTD
  • Moving an Internal DTD to an External File
• Chapter 9: Writing XPath Expressions
• Chapter 10: Working with XQuery in Stylus Studio
• Chapter 11: Composing Web Service Calls
• Chapter 12: Accessing Relational Data as XML
• Chapter 13: Building XML Pipelines
• Chapter 14: Publishing XML Data
• Chapter 15: Integrating with Third-Party File Systems
• Chapter 16: Extending Stylus Studio
• Chapter 17: The Stylus Studio Java API
• Chapter 18: Stylus Studio GUI Reference

Home > Online Product Documentation > Table of Contents > Defining General Entities and Parameter Entities in DTDs

Defining General Entities and Parameter Entities in DTDs

In DTDs, an entity allows you to define a symbol for a value. In the Tree view, you can define general entities and parameter entities. The value of a general entity can be just about anything. It can be

General entities are useful for things that change often, such as the name of a product in development. An entity allows you to change the value in one place and have the corrected value appear everywhere it is needed.

See also Description of Entity and Parameter Entity Properties in DTDs.

When you define a general entity, you specify a symbol that you can use in instance documents. When the XML parser finds a reference to a general entity, it replaces the symbol with the value you specified when you defined the general entity.

When you define a parameter entity, you specify a symbol that you can use elsewhere in the DTD. Again, when the XML parser finds a reference to a parameter entity, it replaces the reference with the value you specified when you defined the parameter entity.

In a DTD, the definition of an entity must appear before a reference to that entity. Therefore, it is good practice to put all entity declarations at the beginning of a DTD.

This section discusses the following topics: