Abstract: Extending managed code framework configurations. A data structure may be implemented in a computing system implementing a managed code framework. A computer readable medium includes a number of data fields stored on the medium and representing a data structure facilitating the extension of configuration parameters used in configuring class types instantiations of class types in the managed code framework. The data structure includes a first data field including data representing an extensions section. The extensions section includes elements including name/class type pairs, the name describing a tagged element in a mark-up document correlated with an application class type. The data structure also includes a second data field containing configuration elements for configuring class types for instantiating class types in a managed code framework. The second data field consumes one or more name/class type pairs from the first data field.