The heap analyzer displays type definitions when you choose the Display
  Type item in the context-sensitive menu for the Memory Map.

  A type definition has the following form:

  LIBRTL\LIB$VM\LIB$GET_VM (Block) has 39 segments
     using 00002160 bytes

  which includes:

   -  LIBRTL\LI$VM\LIB$GET_VM:  The segment type name

   -  (Block):  The type classification (image, block, region, or zone)

   -  39 segments:  Number of segments

   -  00002160 bytes:  Number of bytes

  For information on other heap analyzer screen locations and pop-up
  menus, click the 'On Context' menu item in the heap analyzer Help menu,
  then click the location of interest.

  For information on using the heap analyzer, see the 'On Window' menu
  item in the heap analyzer Help menu.