Portable Custom Interactions - NULL Value

Dear consortium,

I have a question about the IMS Global Portable Custom Interactions Version 1.0 Candidate Final, Appendix A.

I cannot find how to formulate the NULL value using the JSON data format explained in Appendix A. How should it be formulated?

For instance, if we a have a pure scalar null value, what should be the JSON data?

1. { "base": null }

OR

2. { "base": { "boolean": null } }

(our preference goes for solution 1. is our prefered one at Open Assessment Technologies.)

What about NULL values in "list" and "record" containers? How should they be formulated?

All the bests,
Jérôme Bogaerts
Open Assessment Technologies S.A.

Another possibility to indicate a pure NULL value would be,

null

which might be more reliable.