If I have a Tuple which itself contains a nested tuple, how can I emit just that nested tuple?

For example, if you have Map "input1" with Var1(string) and Var2(SomeTuple), to emit just "SomeTuple"-fields as a non-nested tuple use a wildcard Map expression.

In a Map's StreamBase Properties view, Output Settings tab, set: 
  Input Fields: None
  Additional Expressions:
  Action: Add
  Field Name: *
  Expression: Var2.*
as so:


This emits all the nested fields as top-level fields.  

Wildcard expansion of a tuple is described in the Help at:
  TIBCO StreamBase Documentation > StreamBase References > StreamBase Expression Language Features, "Wildcards in EventFlow Expressions"

The '.*' field syntax returns all fields from a nested tuple.