Add text to emphasize that this base class is not exclusively to store fitting parameters.

Author: rayosborn

base_classes/NXparameters.nxdl.xml

@@ -35,10 +35,11 @@
         this base class can also be added to other groups for use in
         other contexts.
 
-        The base class defines a number of attributes that can be used
-        if the parameter values result from, e.g., fitting a function or
-        model to the measured data. If multiple functions are used,
-        there can be additional NXparameter groups for each one.        
+        Although this base class can be used to store any kind of
+        parameter, one possible use case is to store parameters that are
+        refined by a fitting function or model. A number of attributes
+        have been defined to store metadata associated with such a
+        refinment.       
     </doc>
     <attribute name="model">
         <doc>
@@ -61,6 +62,11 @@
                 its value.
             </doc>
         </attribute>
+        <attribute name="description">
+            <doc>
+                A description of what this parameter represents.
+            </doc>
+        </attribute>
         <attribute name="expression">
             <doc>
                 A string representing an expression that can be used to
@@ -75,12 +81,12 @@
                 The initial value of the parameter used in optimization.
             </doc>
         </attribute>
-        <attribute name="max" type="NX_NUMBER">
+        <attribute name="max_value" type="NX_NUMBER">
             <doc>
                 The upper bound of the parameter used in optimization.
             </doc>
         </attribute>
-        <attribute name="min" type="NX_NUMBER">
+        <attribute name="min_value" type="NX_NUMBER">
             <doc>
                 The lower bound of the parameter used in optimization.
             </doc>