--- loncom/html/adm/help/tex/Numerical_Response_Units.tex	2002/07/05 16:12:31	1.1
+++ loncom/html/adm/help/tex/Numerical_Response_Units.tex	2011/06/09 16:04:23	1.4
@@ -1,7 +1,14 @@
+\label{Numerical_Response_Units}
 
 Numerical Response problems can require units. In the problem editing form,
 place the desired unit in the \textbf{Unit} field. For information about
-what units the system accepts, see http://capa4.lite.msu.edu/demolibrary/Links/UnitsSymbolsT2.html.
+what units the system accepts, see \ref{Physical_Units}.
 The computer will accept the answer in any of its accepted unit formats.
 For example, if the answer to a problem is {}``1ft'', the computer will
 accept {}``12in'' as correct.
+
+Additional units can be defined using the ``customunits'' parameter, which is a comma-separated list of unit conversions. For example
+\begin{verbatim}
+peck=2*gallon,bushel=8*gallon,gallon=4.4*L
+\end{verbatim}
+would define the new units peck, bushel, and gallon. The last entry in a conversion chain always needs to be a unit that LON-CAPA already supports.