### What needs to get done At some points in the documentation, like for example in part-properties `build-packages` or `stage-snaps`, the indicated type is `grammar-array` (see for example https://canonical-craft-parts.readthedocs-hosted.com/en/latest/reference/part_properties.html#build-packages). I cannot find a definition of what "grammar-array" is, I think it would be useful to include it somewhere. ### Why it needs to get done At least for me it is not totally clear what grammar-array means without looking into the code.