Thanks, @VKannan17 - that is one of the few places I could find that mention the variables.  Do you think that's the extent of the documentation around 'arc' and 'utils'?  I had actually read that document to be aimed at developers of Extensions for use in Event Forwarding.

When I start to create a new Data Element in an Event Forwarding property with "Data Element Type" set to "Custom Code", the default code includes a notification that the 'arc' and 'utils' variables are available.  Where is the documentation that explains these variables? There are scattered mention...