Techniques for enabling a validating parser to interpret a schema, where that schema may have been extended to multiple levels, and to perform the validation of a structured document according to the extended schema while still allowing a consumer application to request objects or events that are cast at some different level of the schema (including the base schema). Validating the source document according to an extended (i.e., more specific) schema enables improved detection of syntax errors. At the same time, casting objects and events from the parsed document to a level requested by the consumer application allows the consumer to receive only those objects or events for which it is adapted, without requiring the consumer application to include extra code to deal with objects or events it does not recognize in the parser's output. Preferably, the parser simply discards those objects or events which this consumer is not interested in receiving.