Update struct-expr.md
> &nbsp;&nbsp; _StructExprField_ (`,` _StructExprField_)<sup>\*</sup> (`,` _StructBase_ | `,`<sup>?</sup>)
>
> _StructExprField_ :\
-> &nbsp;&nbsp; &nbsp;&nbsp; [IDENTIFIER]\
-> &nbsp;&nbsp; | ([IDENTIFIER] | [TUPLE_INDEX]) `:` [_Expression_]
+> &nbsp;&nbsp; [_OuterAttribute_] <sup>\*</sup>\
+> &nbsp;&nbsp; (\
+> &nbsp;&nbsp; &nbsp;&nbsp; &nbsp;&nbsp; [IDENTIFIER]\
+> &nbsp;&nbsp; &nbsp;&nbsp; | ([IDENTIFIER] | [TUPLE_INDEX]) `:` [_Expression_]\
+> &nbsp;&nbsp; )
>
> _StructBase_ :\
> &nbsp;&nbsp; `..` [_Expression_]
@@ -121,6 +124,7 @@ let a = Gamma; // Gamma unit value.
let b = Gamma{}; // Exact same value as `a`.
```
+[_OuterAttribute_]: attributes.md
[IDENTIFIER]: ../identifiers.md
[TUPLE_INDEX]: ../tokens.md#tuple-index
[_Expression_]: ../expressions.md
