--- ray/doc/notes/ReleaseNotes	2022/08/21 16:20:42	1.421
+++ ray/doc/notes/ReleaseNotes	2023/11/27 22:04:45	1.433
@@ -2575,3 +2575,64 @@ Updated official copyright and license according to ne
 provided by Jean Haemmerle at the LBNL Intellectual Property Office.
 Both were copied verbatim from e-mail I received from Taoning Wang
 on 8/20/2022.
+
+Added -features option to rpict, rtrace, and rcontrib to check
+which features are present or look for specific feature support.
+This addition was suggested by Peter Apian-Bennewitz as an easier
+way to determine which version of Radiance is installed and what
+it supports, and is timely as we begin our refactoring of the
+rendering code.  There are no current plans to add this to rvu.
+
+Added falsecolor -odim, -orct, and -c0 options to overlay grid of
+values on image.  This was requested by Rob Shakespeare.
+
+Added -i* and -o* options in rhcopy for reading rays from the
+standard input and writing rays from holodeck to standard output.
+This will hopefully be useful in combining rholo with rcontrib.
+
+Added further checking for coincident (overlapping) flat surfaces,
+preferring front sides to back sides in the ray intersection
+calculation.  This only applies to rings and faces, as the other
+surface types would have required additional calculations to
+make them work.  Material transparency is still the primary
+consideration, now followed by ray hit side, followed by
+modifier definition order in the input.
+
+Increased octree and object limits to allow scenes with billions
+of primitives.
+
+Made reciprocity averaging default to "off" in bsdf2ttree, as it seems
+to create more problems than it solves.
+
+====================
+Version 6.0
+
+Extensive changes to enable spectral rendering, which defaults to "off"
+to maintain backwards-compatibility with previous versions, with the
+exception of the ambient file format, which is changed.  The MAXCSAMP
+macro, which defaults to 24, sets the maximum number of spectral samples.
+The actual number of samples is set by the "-cs" option, which defaults
+to 3 for rpict, rtrace, and rcontrib.  The latter two programs support
+straight spectral output, but rpict is initially restricted to
+tristimulus output pictures.  New pattern primitives "spectrum",
+"specfile", and "specfunc" have been added as a means to specify
+spectral reflectance, emittance, etc. to materials that still have
+only 3 color channels.  Those RGB channels will still affect the
+spectrum if used.  Unfortunately photon-mapping is currently broken when
+spectral sampling is enabled, but we will fix this as soon as possible.
+Calculation overhead appears to be approximately 10-15% for RGB
+renderings compared to version 5.4a.
+
+Added spectral rendering to rvu as well, and made -cs and -cw
+options standard across the rendering library.  I also brought
+mkillum, ranimove, rsensor, and mksource into the fold.  These
+tools were broken in the initial release.  (Hopefully, they are
+working now, but none have been tested as yet.)
+There was also an indexing bug in the spectral->RGB conversions
+that made reds into blues and vice versa, which has been fixed.
+
+Added i/o for spectral pictures to rmtxop, the first program that can
+ingest them.  (Only rtrace, rcontrib, and rfluxmtx can render them.)
+New symbolic rmtxop -c options, such as RGB, XYZ, S (for scotopic)
+and M (for melanopic) make color conversions simpler.
+Also added spectral picture support to rcrop and radcompare.