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4. Usage

This section describes the various forms of URI references and their usage scenarios.

4.1. URI Reference​

A URI reference can be either a URI or a relative reference.

URI-reference = URI / relative-ref

Key Points:

  • URI references are the most general form
  • Can be absolute or relative
  • Used throughout web technologies

4.2. Relative Reference​

A relative reference takes advantage of the hierarchical syntax (Section 3) to express a URI reference relative to another hierarchical URI.

relative-ref  = relative-part [ "?" query ] [ "#" fragment ]
relative-part = "//" authority path-abempty
              / path-absolute
              / path-noscheme
              / path-empty

Examples:

  • ../resource - parent directory
  • ./file.html - current directory
  • ?query=value - query only
  • #fragment - fragment only

4.3. Absolute URI​

An absolute URI consists of a scheme name followed by a colon, then a scheme-specific part.

absolute-URI  = scheme ":" hier-part [ "?" query ]

Note: Absolute URIs do not include fragments.

4.4. Same-Document Reference​

When a URI reference refers to the same document as the base URI, it is called a same-document reference. The most common form is a fragment reference.

Example: #section1

4.5. Suffix Reference​

A suffix reference is a relative reference that contains only path segments and optional query and/or fragment.

Examples:

  • file.txt
  • dir/file.html?key=value

Next Chapter: 5. Reference Resolution - How to resolve relative references

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