git revision: 68ad948

The following definition generates a parser errror:

FooChoice = FooA / FooB / FooC
FooA = 1
FooB = 2
FooC = 3

SomeStructure = (
   foo: ?FooChoice .default FooA
)

replacing the definition with an inline definition

SomeStructure = (
   foo: ?((FooA: 1) / (FooB: 2) / (FooC: 3)) .default FooA
)

yields the same error. Also replacing the default value with the numerical representation (1 in this case).