[devel]
  Added some commentary about PNG_EXPORT in png.h and pngconf.h
diff --git a/png.h b/png.h
index 6a5309d..023c477 100644
--- a/png.h
+++ b/png.h
@@ -1,7 +1,7 @@
 
 /* png.h - header file for PNG reference library
  *
- * libpng version 1.5.0beta56 - November 25, 2010
+ * libpng version 1.5.0beta56 - December 6, 2010
  * Copyright (c) 1998-2010 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
@@ -11,7 +11,7 @@
  * Authors and maintainers:
  *   libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat
  *   libpng versions 0.89c, June 1996, through 0.96, May 1997: Andreas Dilger
- *   libpng versions 0.97, January 1998, through 1.5.0beta56 - November 25, 2010: Glenn
+ *   libpng versions 0.97, January 1998, through 1.5.0beta56 - December 6, 2010: Glenn
  *   See also "Contributing Authors", below.
  *
  * Note about libpng version numbers:
@@ -173,7 +173,7 @@
  *
  * This code is released under the libpng license.
  *
- * libpng versions 1.2.6, August 15, 2004, through 1.5.0beta56, November 25, 2010, are
+ * libpng versions 1.2.6, August 15, 2004, through 1.5.0beta56, December 6, 2010, are
  * Copyright (c) 2004, 2006-2010 Glenn Randers-Pehrson, and are
  * distributed according to the same disclaimer and license as libpng-1.2.5
  * with the following individual added to the list of Contributing Authors:
@@ -285,7 +285,7 @@
  * Y2K compliance in libpng:
  * =========================
  *
- *    November 25, 2010
+ *    December 6, 2010
  *
  *    Since the PNG Development group is an ad-hoc body, we can't make
  *    an official declaration.
@@ -349,7 +349,7 @@
 /* Version information for png.h - this should match the version in png.c */
 #define PNG_LIBPNG_VER_STRING "1.5.0beta56"
 #define PNG_HEADER_VERSION_STRING \
-     " libpng version 1.5.0beta56 - November 25, 2010\n"
+     " libpng version 1.5.0beta56 - December 6, 2010\n"
 
 #define PNG_LIBPNG_VER_SONUM   15
 #define PNG_LIBPNG_VER_DLLNUM  15
@@ -882,6 +882,21 @@
  * the place to find out how to use libpng.  See libpng-manual.txt for the
  * full explanation, see example.c for the summary.  This just provides
  * a simple one line description of the use of each function.
+ *
+ * The PNG_EXPORT macro used below is defined in pngconf.h and in
+ * the *.dfn files in the scripts directory.
+ *
+ *   PNG_EXPORT(type, name, (args), [attributes], ordinal);
+ *
+ *       type:       return type of the function
+ *       name:       function name
+ *       args:       function arguments, with types
+ *       attributes: optional function attributes
+ *       ordinal:    ordinal that is used while building
+ *                   *.def files. The ordinal value is only
+ *                   relevant when preprocessing png.h with
+ *                   the *.dfn files for building symbol table
+ *                   entries.
  */
 
 /* Returns the version number of the library */