To: J3                                                     J3/17-191
From: Steve Lionel
Subject: Redundant IMPLICIT NONE specs
Date: 2017 August 16

Reference: 17-007r2

Introduction
============

R863 for the IMPLICIT statement includes:

IMPLICIT NONE [ ( [ implicit-none-spec-list ] ) ]

where implicit-none-spec is EXTERNAL or TYPE (R866). A constraint
is needed to prohibit repeating an implicit-none-spec in a
list, otherwise one could have:

IMPLICIT NONE (EXTERNAL, EXTERNAL, TYPE, TYPE)

Edit
====

Insert a constraint:

[120:20+] C890+ (R863) The same implicit-none-spec shall not appear
more than once in a given implicit-stmt.