1. A system comprising: a web application configured to: receive a request that references a first uniform resource locator (URL) by which a document is locatable for display in a browser, the first URL corresponding to a first state in which the document has a first appearance; and provide the document in its first state with its first appearance to the browser in response to the request and based on the first URL corresponding to the first state, the document in its first state including a control usable to invoke a second state in which the document has a second appearance; and a processor configured by a validation module to: detect use of the control to invoke the second state of the document, the control referencing a second URL by which the document is locatable for display in the browser, the browser displaying the document in its second state with its second appearance in response to the use of the control; and map the second state of the document to the second URL by storing a correspondence relationship between the second URL and data that defines the second appearance of the document.