public string GetCallbackEventReference(string QueryStringExpression);

Parameters

QueryStringExpression
An expression that is evaluated in script code and embedded as the second parameter.
The value of this second parameter is interpreted as a QueryString to the URL that
is fired in response to the request to the server.

This expression can be a static string or any value or expression that is in scope
at the time of calling the event method. The expression must evaluate to a string

Example:
string GetCallbackEventReference("'CustomerId=' + forms[0].txtCustomerId.value + "'");

A callback event reference result looks like this:

ControlID_StartCallback(event,'CustomerId=_12312')

See also:

Class HoverPanel