I think we should cover also the following cases:

1. Using type at the first level (to ensure that the XSD checker will do a pass for that XML to ensure that `<contextValue type="vector">` is ok.
2. The error case of repeating the same child tag twice in a not vector element, e.g.:

```
<levelX>
  <valueY>1</valueY>
  <valueY>2</valueY>
</levelX>
```