Index: trunk/doc/pslib/psLibSDRS.tex
===================================================================
--- trunk/doc/pslib/psLibSDRS.tex	(revision 2189)
+++ trunk/doc/pslib/psLibSDRS.tex	(revision 2190)
@@ -1,3 +1,3 @@
-%%% $Id: psLibSDRS.tex,v 1.141 2004-10-21 22:52:38 price Exp $
+%%% $Id: psLibSDRS.tex,v 1.142 2004-10-22 00:14:20 price Exp $
 \documentclass[panstarrs,spec]{panstarrs}
 
@@ -3441,15 +3441,17 @@
 \begin{verbatim}
 psTime *psTimeAdd(const psTime *time, psF64 delta);
-psF64 psTimeSubtract(const psTime *time1, const psTime *time2);
+psF64 psTimeSubtract(const psTime *time, psF64 delta);
 psF64 psTimeDelta(const psTime *time1, const psTime *time2);
 \end{verbatim}
 \code{psTimeAdd} adds some time to a \code{psTime}.
 \code{psTimeSubtract} subtracts two times.  \code{psTimeDelta} gives
-the absolute time difference between two times.
+the difference between times \code{time1} and \code{time2} (which may
+be negative).
 
 Time math may only be done on the \code{psTime} TAI type, and so the
 functions shall internally convert the \code{psTime} inputs to TAI
 before performing the math.  The type of the time returned by
-\code{psTimeAdd} shall be the same as that of the input \code{time}.
+\code{psTimeAdd} and \code{psTimeSubtract} shall be the same as that
+of the input \code{time}.
 
 \subsubsection{Time Tables}