Thank you Mary.
After some digging, searching and trial and errors, I answered my own question...
For the benefits of others, here it is:
As per the documentation for the "offline quiz", it was requesting for the "id number" as the reference into the Moodle database. "id number" is a field in the "mdl_user" table and in my case is not filled in for any of the users (don't know exactly what it relates to...).
This reference to the Moodle database can be other field in the "mdl_user" table; I have used another one (unique) to identify the participants to the offline quiz. This field needs to be identified into the "offline quiz" settings:
- Site administration
- / ▶︎ Plugins
- / ▶︎ Activity modules
- / ▶︎ Offline Quiz --> 1. User identification
Hence from then on, pertaining documents for the offline quiz had this id along with participants. And upon scanned documents review in Moodle, the reference was completed.
This plugin is quite impressive once mastered. Kudos to the designers.
Louis.