--- ray/doc/man/man1/rtcontrib.1	2005/10/06 05:49:44	1.12
+++ ray/doc/man/man1/rtcontrib.1	2005/10/11 16:54:26	1.14
@@ -1,4 +1,4 @@
-.\" RCSid "$Id: rtcontrib.1,v 1.12 2005/10/06 05:49:44 greg Exp $"
+.\" RCSid "$Id: rtcontrib.1,v 1.14 2005/10/11 16:54:26 greg Exp $"
 .TH RTCONTRIB 1 5/25/05 RADIANCE
 .SH NAME
 rtcontrib - compute contribution coefficients in a RADIANCE scene
@@ -7,6 +7,8 @@ rtcontrib - compute contribution coefficients in a RAD
 [
 .B "\-n nprocs"
 ][
+.B \-fo
+|
 .B \-r
 ][
 .B "\-e expr"
@@ -74,9 +76,12 @@ specification.
 If a destination begins with an exclamation mark ('!'), then
 a pipe is opened to a command and data is sent to its standard input.
 Otherwise, the destination is treated as a file.
-An existing file of the same name is clobbered, unless the
+An existing file of the same name will not be clobbered, unless the
+.I \-fo
+option is given.
+If instead the
 .I \-r
-option is specified, in which case data recovery is attempted.
+option is specified, data recovery is attempted on existing files.
 If an output specification contains a "%s" format, this will be
 replaced by the modifier name.
 The
@@ -89,8 +94,11 @@ The actual bin number is computed at run time based on
 and surface intersection, as described below.
 If the number of bins is known in advance, it should be specified with the
 .I \-bn
-option, especially for output files containing multiple bins.
-Set this to 0 if the number of bins is unknown (the default).
+option, and this is critical for output files containing multiple values
+per record.
+Since bin numbers start from 0, the bin count is always equal to
+the last bin plus 1.
+Set the this value to 0 if the bin count is unknown (the default).
 The most recent
 .I \-b,
 .I \-bn