Library /sys$common/syshlp/sca$menu.hlb sca__query_ds  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  Choose the Data Structures menu item from the Query pull-down menu to
  change the current query and result window to Data Structures Query
  and Result windows.  The Data Structures Query window lets you
  specify a data structures query, the result of which shows typing
  relationships between data structures and types.