--- loncom/html/adm/help/tex/Function_Plot_Response_Evaluation_Rule.tex	2011/10/13 01:54:17	1.2
+++ loncom/html/adm/help/tex/Function_Plot_Response_Evaluation_Rule.tex	2011/10/14 00:40:28	1.3
@@ -16,7 +16,7 @@ Overview - This box is used to create a
 
 ``Relationship''  - The heart of the rule.  This choice determines whether the chosen 'Function' is greater than, less than, equal to, etc. a certain 'value'.
 
-``Value'' - See above.  It is also possible to choose 'not defined', in the event the answer should not have a value for the given domain. Within the value argument, the function itself can be evaluated using \&fpr\_f(), its derivative using \&fpr\_dfdx, and its second derivative using \&fpr\_d2fdx2().
+``Value'' - See above.  It is also possible to choose 'not defined', in the event the answer should not have a value for the given domain. Within the value argument, the function itself can be evaluated using \&fpr\_f(), its derivative using \&fpr\_dfdx(), and its second derivative using \&fpr\_d2fdx2(). The value of a previously defined label can be retrieved using the function \&fpr\_val(), e.g., \&fpr\_val('positive'). Previous defined values from script blocks can be retrieved as normal variables, e.g., \$x.
 
 ``Percent error'' - This allows for a margin of error in the y-direction.  For instance, if the rule requires that the derivative be equal to 5, the server will accept values close enough to 5 that are within the percent error defined here. Note: Choosing 10\% would not mean that the answer is correct as long as it is within the range 4.5-5.5.  Instead, the percent corresponds to the total size of the graph.  For the function itself, the 'percent error' is multiplied by the ymax-ymin; for the first derivative, it's multiplied by (ymax-ymin)/(xmax-xmin); for the second derivative, it's multiplied by (ymax-ymin)/(xmax-xmin)^2; and for the integral, it's multiplied by (ymax-ymin)*(xmax-xmin).