Signature:

  SUBROUTINE h5oopen_by_idx_f(loc_id, group_name, index_type, order, n, &
       obj_id, hdferr, lapl_id)
    IMPLICIT NONE
    INTEGER(HID_T)  , INTENT(IN)            :: loc_id
    CHARACTER(LEN=*), INTENT(IN)            :: group_name
    INTEGER         , INTENT(IN)            :: index_type
    INTEGER         , INTENT(IN)            :: order
    INTEGER(HSIZE_T), INTENT(IN)            :: n
    INTEGER(HID_T)  , INTENT(OUT)           :: obj_id
    INTEGER         , INTENT(OUT)           :: hdferr
    INTEGER(HID_T)  , INTENT(IN) , OPTIONAL :: lapl_id

Inputs:

  loc_id      - A file or group identifier.
  group_name  - Name of group, relative to loc_id, in which object is located.
  index_type  - Type of index by which objects are ordered.
  order       - Order of iteration within index, NOTE: zero-based.
  n           - Object to open.

Outputs:

  obj_id      - An object identifier for the opened object.
  hdferr      - Returns 0 if successful and -1 if fails.

Optional parameters:

  lapl_id     - Link access property list.