sentence is not complete

[wanghaisheng]

in section 5 ### Field Selections on Objects, Interfaces, and Unions Types,
" Because fields are not declared on unions, direct field selection on union-typed selection set. This is true even if concrete implementors of the union define the fieldName."
what does "direct field selection on union-typed selection set." mean?

[leebyron]

Thanks for pointing this out! I just re-wrote this section to be more clear, I hope it helps.

[wanghaisheng]

@leebyron .why the following is invalid.it is indirectly queried through a fragment ,the union concrete implementors instead of the union itself.（your original words are Fields from a union-typed selection set must only be queried indirectly via
a fragment）

fragment directFieldSelectionOnUnion on CatOrDog {
   name
   barkVolume
 }