+/****************************************************************************
+RETURNS:
+The string value of the variable
+
+PARAMETERS:
+parms - Optional parameter string passed from parm= field in HTML
+
+REMARKS:
+To create new variables for the #echo HTML preprocessing directives
+you need to derive classes from wxEchoVariable and override the
+pure virtual GetValue function. However this should not be done directly
+but by using the BEGIN_ECHO_VARIABLE and END_ECHO_VARIABLE macros
+
+SEE ALSO:
+wxEchoPrep, BEGIN_ECHO_VARIABLE, END_ECHO_VARIABLE
+****************************************************************************/
+typedef wxString (*wxEchoVariableGetValueFn)(const char *parms);
+