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.