A URI path parameter is part of a path segment that occurs after its name. Path parameters offer a unique opportunity to control the representations of resources. Since they can't be manipulated by standard Web forms, they have to be constructed out of band. Since they're part of the path, they're sequential, unlike query strings. Most importantly, however, their behaviour is not explicitly defined.

When defining constraints for the syntax of path parameters, we can take these characteristics into account, and define parameters that stack sequentially, and each take multiple values.

In the last paragraph of section 3.3, The URI specification suggests employing the semicolon ;, equals = and comma , characters for this task. Therefore: