Question

The structure of an ________ document is described by its corresponding Document Type Definition (DTD).

Short answer

XML

Step-by-step solution

Read and Analyze the Question

Carefully read the question to understand what is being asked. Here, we are asked about the type of document whose structure is defined by a Document Type Definition (DTD).

Key concepts

XML document

An XML document, short for eXtensible Markup Language document, is a file format used to store and transport data. XML is both human-readable and machine-readable, making it a versatile choice for various applications such as web services, RSS feeds, and document storage systems. Every XML document contains a prolog, a root element, and a structure made up of nested elements.
The prolog comprises information about the XML version and character encoding used. The root element is the topmost element in the structure that contains all other elements, providing a single hierarchy. What sets XML apart is its flexibility to create custom tags, giving users a powerful tool to represent data structures and hierarchies according to their needs.
Despite its flexibility, XML comes with a necessity to follow a defined format. This ensures data is consistently readable and processable by different systems. Given this, the role of a Document Type Definition comes into play.

DTD structure

A DTD, or Document Type Definition, is a set of defined rules and specifications that dictate the structure of an XML document. It acts as a blueprint outlining what elements can appear in a document, the order of these elements, and their attributes. A DTD specifies:

• Elements that must be in the document
• Attributes for each element
• The nesting order of elements
• Data types for element attributes

When composing a DTD, these rules are embedded within the XML or as a separate file, facilitating both internal and external definitions. By doing so, it standardizes how data is arranged and ensures consistency across different XML documents.
Typically, the syntax of a DTD is straightforward, utilizing a few key tags and symbols. Learn these conventions, and you'll be able to construct or interpret XML documents with greater ease.

markup language

The term 'markup language' refers to a system for annotating a document in a way that is syntactically distinguishable from its text. XML, as a markup language, allows for data encapsulation inside tags that provide contextual meaning to the data.
Tags are surrounded by angle brackets and provide an intuitive way of representing hierarchy and relationships between data pieces. Examples include: