1. A method for converting a document encoded in a markup language into a format for mapping to a database table, the method including the steps of: replacing the content of at least one node in said document stored in a first storage unit with a placeholder and storing said replaced content in a separate data storage unit associated with the corresponding node, the node being an instance of a node element selected from a node element set; and modifying a formal definition of markup rules associated with said document to recognise said placeholder.