--- ray/doc/notes/ReleaseNotes	2014/09/15 16:49:08	1.247
+++ ray/doc/notes/ReleaseNotes	2014/11/21 00:53:52	1.251
@@ -1975,3 +1975,31 @@ Added default specular lobe to BSDF interpolation.
 Set minimum number of shadow checks before direct optimization (4).
 
 (Above changes included in 4.2.1 patch release.)
+
+****** COMPATIBILITY CHANGE ********
+Made header input and output the default behavior for dctimestep and
+genskyvec.
+
+****** COMPATIBILITY CHANGE ********
+Changed pabopto2bsdf default behavior to add 90-degree rotation
+to bring pgII's definition of "up" in line with Klems axis
+conventions.  Introduced a new header variable "upphi" to
+control this added rotation.  Using "#upphi 90" in each
+BSDF input file gets back the original behavior, where it
+assumes that the up direction is 90-degrees from the X-axis.
+The default value of 0 corresponds to PAB's definition of
+the X-axis as being "up".
+
+Fixed bug in rsensor related to having many rows (altitude) and
+few columns (azimuth) in sensitivity file.
+
+Fixed floating point round-off error in new Hessian calculation
+for some sytems (Windows, primarily).
+
+Fixed bug in tensor tree BSDF code that caused bus error on
+some systems, and may have been source of other errors as well.
+
+(Above changes included in 4.2.2 patch release.)
+
+Improved ambient extrapolation to avoid zero values.  Actual
+threshold set to 5% of recorded value.