Vector_Subscripts

 A vector subscript is a rank-one array of integer values (within
 the declared bounds for the dimension).  It is used to select a
 sequence of elements from a parent array.  The sequence does not
 have to be in order, and it can contain duplicate values.

 For example, A is a rank-two array of shape (4,6).  B and C are
 rank-one arrays of shape (2) and (3), respectively, with the
 following values:

   B = (/1,4/)
   C = (/2,1,1/)         ! Will result in a many-one 
                         !   array section

 Array section A(3,B) consists of elements A(3,1) and A(3,4).  Array
 section A(C,1) consists of elements A(2,1), A(1,1), and A(1,1).
 Array section A(B,C) consists of the following elements:

   A(1,2)   A(1,1)   A(1,1)
   A(4,2)   A(4,1)   A(4,1)

 An array section with a vector subscript that has two or more
 elements with the same value is called a many-one array section.  A
 many-one section must not appear on the left of the equals sign in
 an assignment statement, or as an input item in a READ statement.

 The following assignments to C also show examples of vector
 subscripts:

   INTEGER A(2), B(2), C(2)
   ...
   B    = (/1,2/)
   C(B) = A(B)
   C    = A((/1,2/))        

 An array section with a vector subscript must not be any of the
 following:

  o  An internal file

  o  An actual argument associated with a dummy array that is
     defined or redefined (if the INTENT attribute is specified, it
     must be INTENT(IN))

  o  The target in a pointer assignment statement


 If the sequence specified by the vector subscript is empty, the
 array section has a size of zero.