Tree patterns do just that, and XPath provides a convenient syntax in which to express those patterns.Validation using tree patterns is a two-step process: Both the candidate object selection, and the assertions can be defined in terms of XPath expressions.
Having highlighted the fact that the existing schema paradigm can only express constraints among data items in terms of the child and sibling axes, it is natural to consider whether an alternate paradigm might allow a schema author to exploit these additional relationships to define additional types of constraint amongst document elements.A trivial XML vocabulary is introduced for the purposes of generating examples.The later sections in this paper provides an overview of the open source XSLT framework used to implement the Schematron language.As the XPath specification [XPath] shows, there are many possible kinds of relationship, known as 'axes'.While XML does include an ID/IDREF mechanism which allows for cross-referencing between elements, and hence another form of relationships, it only weakly binds those elements.Expressing validation rules using patterns is often easier than defining the same rule using a content model.
Tree patterns are collected together to form a Schematron schema.
The Schematron conformance language for custom implementation is also introduced.
The paper completes with some suggestions of possible future extensions.
I created a quick form with a Text Box, a Button, and two labels occupying the same location to report the answer by making one or the other visible. Click If -- Test for numeric characters -- lbl Not Int. Visible = True End Sub Private Sub Test String In_Text Changed( By Val sender As System.
All the tests were similar to this: Private Sub btn Validate String_Click( By Val sender As System.
Abstract Schematron [Schematron] is a structural based validation language, defined by Rick Jelliffe, as an alternative to existing grammar based approaches.