INDEXED_MIXED_IO is a Compaq Ada package that provides input-output
    operations for access to and from indexed files whose elements
    contain values of different types.

    All of the file management and item input-output operations are
    also provided by this package (see HELP Ada Language_Topics File_
    Management and HELP Ada Language_Topics Item_Input_Output)

    This package provides a generic READ_BY_KEY procedure, which
    defines input for the given element type. This procedure must
    be instantiated with an actual type parameter for the generic
    parameter KEY_TYPE; it may be instantiated with or without a
    value for the generic parameter DEFAULT_KEY_NUMBER. The range
    of values for DEFAULT_KEY_NUMBER is 0 to 254; a value of 0 (the
    default) designates the primary key.

    If the RELATION parameter to the READ_BY_KEY procedure is
    specified, it must have a value of EQUAL_NEXT, EQUAL, or NEXT
    (the default is EQUAL).

  Additional Information (explode) :

• READ
• WRITE
• UPDATE
• UNLOCK
• DELETE_ELEMENT
• END_OF_FILE