--- ray/doc/man/man1/dctimestep.1	2025/03/24 17:20:36	1.22
+++ ray/doc/man/man1/dctimestep.1	2025/03/27 01:26:55	1.23
@@ -1,4 +1,4 @@
-.\" RCSid $Id: dctimestep.1,v 1.22 2025/03/24 17:20:36 greg Exp $"
+.\" RCSid $Id: dctimestep.1,v 1.23 2025/03/27 01:26:55 greg Exp $"
 .TH DCTIMESTEP 1 12/09/09 RADIANCE
 .SH NAME
 dctimestep - compute annual simulation time-step(s) via matrix multiplication
@@ -15,9 +15,9 @@ dctimestep - compute annual simulation time-step(s) vi
 ][
 .B "\-y yres"
 ][
-.B "\-i{f|d}
+.B "\-i{a|f|d}
 ][
-.B "\-o{f|d|c}
+.B "\-o{a|f|d|c}
 ]
 .B DCspec
 [
@@ -106,15 +106,13 @@ using quotes and a beginning exclamation point ('!').
 The standard output of
 .I dctimestep
 is either a color vector with as many RGB triplets
-as there are rows in the View matrix, or a combined
-.I Radiance
+as there are rows in the View matrix, or a combined Radiance
 picture.
 Which output is produced depends on the first argument.
 A regular file name will be loaded and interpreted as a matrix to
 generate a color results vector.
 A file specification containing a '%d' format string will be
-interpreted as a list of
-.I Radiance
+interpreted as a list of Radiance
 component pictures, which will be summed according to the computed
 vector.
 .PP
@@ -162,7 +160,7 @@ the Winter solstice at 2pm:
 .IP "" .2i
 gensky 12 21 14 | genskyvec | dctimestep IllPts.vmx Blinds20.xml Window1.dmx > Ill_12-21-14.dat
 .PP
-To compute Window2's contribution to an interior view at 12 noon on the Summer solstice:
+To compute Window2's contribution to an interior view at 12 noon on the summer solstice:
 .IP "" .2i
 gensky 6 21 12 | genskyvec | dctimestep view%03d.hdr Blinds30.xml
 Window2.dmx > view_6-21-12.hdr
@@ -204,9 +202,18 @@ equivalent invocation of
 or
 .I rcomb(1),
 which perform all operations on 64-bit "double" values.
+.PP
+.I Dctimestep
+does not accept on input or produce on output Radiance
+spectral pictures.
+This is a limitation of the implementation and its underlying
+data representation.
+Use instead the similar
+.I pvsum(1)
+tool for spectral input and output.
 .SH AUTHOR
 Greg Ward
 .SH "SEE ALSO"
-gendaymtx(1), genskyvec(1), getinfo(1),
-mkillum(1), rcollate(1), rcomb(1), rcontrib(1), rcrop(1),
+dcglare(1), gendaymtx(1), genskyvec(1), getinfo(1), mkillum(1),
+pvsum(1), ra_rgbe(1), rcollate(1), rcomb(1), rcontrib(1), rcrop(1),
 rfluxmtx(1), rmtxop(1), rtrace(1), vwrays(1)