--- ray/doc/ray.1	2014/07/31 18:32:41	1.26
+++ ray/doc/ray.1	2015/12/01 16:58:16	1.28
@@ -1,8 +1,8 @@
-.\" RCSid "$Id: ray.1,v 1.26 2014/07/31 18:32:41 greg Exp $"
+.\" RCSid "$Id: ray.1,v 1.28 2015/12/01 16:58:16 greg Exp $"
 .\" Print using the -ms macro package
-.DA 07/31/2014
+.DA 09/18/2015
 .LP
-.tl """Copyright \(co 2014 Regents, University of California
+.tl """Copyright \(co 2015 Regents, University of California
 .sp 2
 .TL
 The
@@ -1155,6 +1155,7 @@ between 0.1 (for tightly spaced characters) and 0.3 (f
 Mixtures
 .PP
 A mixture is a blend of one or more materials or textures and patterns.
+Blended materials should not be light source types or virtual source types.
 The basic types are given below.
 .LP
 .UL Mixfunc