Steve,

Our CommonEvent and DiagnosticEvent provide a bunch of context parameters
which are useful when building your own custom schema.  So that's certainly
a valid starting place for creating your own events.  

If you like the way we organized the standard events which sit on top of
those events, then extending them is the right thing to do.  However, given
that we provide the full source code, you're fairly unlimited in terms of
what you can do.

It's also very possible to discard all the events, derive from BaseEvent
and build your own events from scratch.  One reason is if you decide you
want a set of trace events which are much lighter weight (don't include the
10-15 properties which we normally put on all events).

So, in summary -- we don't have explicit rules about what the right thing
to do is in terms of schema customization.  It really depends on your
requirements, and we're interested to know what folks end up doing in this
area, so we have a better idea of best practices for the future.

David [MSFT]

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