Hi Rachel,
Apologies but I forgot to respond to one of your comments on the draft version of Chapter 7.
The comment in question related to why the description of the reference intersection operator is perhaps a little more detailed than that of the reference concatenation operator.
I think this difference is a result of the subjective opinions of previous authors and reviewers (including me) who considered that the reference intersection operator could prove a little more difficult to understand. Hence the inclusion of an illustration and extra examples. I am not aware of any user-based metrics that would suggest that one of the operators is likely to be used more often than the other.
I didn’t update either sub-section to address this comment and I hope that is okay with you.
Regards,
Steve