Improving specs

I would like to suggest that the LTI specs could be improved by being more explicit about the data types permitted for each claim or JSON element. For example, I recently received a response to a request sent to a platform's Result Service endpoint which gave the userId properties as integer values. The spec does not seem to explicitly state that the value must be a string, but all the examples in the spec use string values, and since it should be the same value as used in the sub claim of a launch message from that user (which must be a string value according to the JWT spec), and the same value is used for the user_id property in the Names and Role Provisioning Services, then I would expect the userId property in the Assignment and Grade Services specs to also be string values. This is just one example of where making data types more explicit in the specs would be very helpful. Thanks.