A reference to a component of a derived-type structure takes the
  following form:

    parent [%component [(s-list)]]... %component [(s-list)]

    parent    Is the name of a scalar or array of derived type.
              The percent sign (%) is called a component selector.

    component Is the name of a component of the immediately
              preceding parent or component.

    s-list    Is a list of one or more subscripts. If the list
              contains subscript triplets or vector subscripts,
              the reference is to an array section.

              Each subscript must be a scalar numeric expression
              with a value that is within the bounds of its
              dimension.

              The number of subscripts in any s-list must equal
              the rank of the immediately preceding parent or
              component.

  Each parent or component (except the rightmost) must be of derived
  type.

  The parent or one of the components can have nonzero rank (be an
  array).  Any component to the right of a parent or component of
  nonzero rank must not have the POINTER attribute.

  The rank of the structure component is the rank of the part (parent
  or component) with nonzero rank (if any); otherwise, the rank is
  zero.  The type and type parameters (if any) of a structure
  component are those of the rightmost part name.

  The structure component must not be referenced or defined before
  the declaration of the parent object.

  If the parent object has the INTENT, TARGET, or PARAMETER
  attribute, the structure component also has the attribute.

1  –  Examples

  The following example shows a derived-type definition with two
  components:

    TYPE EMPLOYEE
      INTEGER ID
      CHARACTER(LEN=40) NAME
    END TYPE EMPLOYEE

  The following shows how to declare a variable CONTRACT of type
  EMPLOYEE:

    TYPE(EMPLOYEE) :: CONTRACT

  Note that both examples started with the keyword TYPE.  The first
  (initial) statement of a derived-type definition is called a
  derived-type statement, while the statement that declares a
  derived-type object is called a TYPE statement.

  The following example shows how to reference component ID of parent
  structure CONTRACT:

    CONTRACT%ID

  The following example shows a derived type with a component that is
  a previously defined type:

    TYPE DOT
      REAL X, Y
    END TYPE DOT
    ....
    TYPE SCREEN
      TYPE(DOT) C, D
    END TYPE SCREEN

  The following declares a variable of type SCREEN:

    TYPE(SCREEN) M

  Variable M has components M%C and M%D (both of type DOT); M%C has
  components M%C%X and M%C%Y of type REAL.

  The following example shows a derived type with a component that is
  an array:

    TYPE CAR_INFO
      INTEGER YEAR
      CHARACTER(LEN=15), DIMENSION(10) :: MAKER
      CHARACTER(LEN=10) MODEL, BODY_TYPE*8
      REAL PRICE
    END TYPE
    ...
    TYPE(CAR_INFO) MY_CAR

  Note that MODEL has a character length of 10, but BODYTYPE has a
  character length of 8.  You can assign a value to a component of a
  structure; for example:

    MY_CAR%YEAR = 1985

  The following shows an array structure component:

    MY_CAR%MAKER

  In the preceding example, if a subscript list (or substring) was
  appended to MAKER, the reference would not be to an array structure
  component, but to an array element or section.

  Consider the following:

    TYPE CHARGE
      INTEGER PARTS(40)
      REAL LABOR
      REAL MILEAGE
    END TYPE CHARGE

    TYPE(CHARGE) MONTH
    TYPE(CHARGE) YEAR(12)

  Some valid array references for this type follow:

    MONTH%PARTS(I)           ! An array element
    MONTH%PARTS(I:K)         ! An array section
    YEAR(I)%PARTS            ! An array structure component
                             !  (a whole array)

    YEAR(J)%PARTS(I)         ! An array element
    YEAR(J)%PARTS(I:K)       ! An array section
    YEAR(J:K)%PARTS(I)       ! An array section
    YEAR%PARTS(I)            ! An array section

  The following example shows a derived type with a pointer component
  that is of the type being defined:

    TYPE NUMBER
      INTEGER NUM
      TYPE(NUMBER), POINTER :: BEFORE_NUM
      TYPE(NUMBER), POINTER :: AFTER_NUM
    END TYPE

  A type such as this can be used to construct linked lists of
  objects of type NUMBER.

  The following example shows a private type:

    TYPE, PRIVATE :: SYMBOL
      LOGICAL TEST
      CHARACTER(LEN=50) EXPLANATION
    END TYPE SYMBOL

  This type is private to the module.  The module can be used by
  another scoping unit, but type SYMBOL is not available.

  The following example shows a derived-type definition that is
  public with components that are private:

    MODULE MATTER
      TYPE ELEMENTS
        PRIVATE
        INTEGER C, D
      END TYPE
    ...
    END MODULE MATTER

  In this case, components C and D are private to type ELEMENTS, but
  type ELEMENTS is not private to MODULE MATTER.  Any program unit
  that uses the module MATTER can declare variables of type ELEMENTS,
  and pass as arguments values of type ELEMENTS.

  This design allows you to change components of a type without
  affecting other program units that use the module.

  If a derived type is needed in more than one program unit, the
  definition should be placed in a module and accessed by a USE
  statement whenever it is needed, as follows:

    MODULE STUDENTS
      TYPE STUDENT_RECORD
      ...
      END TYPE
    CONTAINS
      SUBROUTINE COURSE_GRADE(...)
      TYPE(STUDENT_RECORD) NAME
      ...
      END SUBROUTINE
    END MODULE STUDENTS
    ...

    PROGRAM SENIOR_CLASS
      USE STUDENTS
      TYPE(STUDENT_RECORD) ID
      ...
    END PROGRAM

  Program SENIOR_CLASS has access to type STUDENT_RECORD, because it
  uses module STUDENTS.  Module procedure COURSE_GRADE also has
  access to type STUDENT_RECORD, because the derived-type definition
  appears in its host.