The current syntax for non-decimal numbers is awful, undocumented and weak. We should devise a deprecation process and replace it with, for instance, the one used in PHP. I think there won't be many use cases, but we still need to be careful in order to avoid breaking existing filters.
- Check production use with info logging
- Introduce new syntax as experimental
- Ensure that no filter in production is already unintendedly using the new syntax
- Bump logging for old syntax to deprecated, in MW version X
- Remove old path, leave only the new one, in MW version X+1