Server audit|OPC UA Standard|Forum|OPC Foundation

I try to implement audit events for method calls on my server. What is in the specification is not really much (or at least not understandable for me), so I'd like to ask a few questions:

1. Is there any client supporting that? The client has to create the audit entry log and provide the id to the server., at least UaExpert seems to not be able to do that.
2. What should the server do when audit is enabled but the server does not provide a audit entry id? Leave it empty? Create some internal entry id?
3. If a single method on the server creates multiple internal calls (i.e. if the method creates and starts something like a batch file that executes multiple methods in series, maybe also on different servers), should the same audit entry id be used for all calls? That would make it traceable, so everything the one call caused can be identified with this audit entry id. But can a client handle that?
4. What should a audit entry id look like?
5. If I forward an audit event in an aggregated server, should I use the same event id?