A method and system are provided for using icons to show the validity of markup language elements applicable to a computer-generated document. A user of a computer-generated document such as a word processing document attaches a schema to the document setting out the rules and procedures with which the document may be annotated with markup language elements for structuring portions of the document. According to one aspect of the invention, the user attaches an Extensible Markup Language (XML) schema to the document for setting the data types, data structures and XML elements rules for the document so that the user may annotate the document with XML structure. When the user begins to annotate the document with a desired markup language structure, such as XML structure, an application pane is displayed to the user to provide the user with assistance in applying allowable XML elements at allowable locations and in allowable order and number. A series of icons are presented alongside the presented elements in the application pane to indicate the level of validity of a given element based on the editing context and location in the document.