some quick questions about scxml

Hi,
I'm just learning about scxml and found some questions about SCXML draft
dated 24 January 2006 (http://www.w3.org/TR/scxml/):

1) I wonder why <invoke> can only be used under <state>, unlike <send> that
can be used in either <onentry> or <onexit>. What if I want to invoke an
external module only on exit?

2) The xsd doesn't seem to allow custom tags in <onentry> or <onexit>
element, even though the spec permits it, because "executablecontent" group
in the xsd seems to miss a <xsd:any> definition.

3) Element <normalize> (F.3 Example of Invoke and finalize) doesn't seem to
be described in spec or defined in the scxml xsd.

Thanks.

Li Li