What are the Lumen External Tool/LTI Apps?

Lumen supports 3 types of courses with the following configurations:

Waymaker:
- - Lumen Platform (basic launch LTI)
  - Lumen Waymaker (used for the Study Plan functionality)
  - Lumen OHM (used for calculations in courses like Microeconomics)
Candela: Lumen Platform only
Lumen OHM: Lumen OHM only

Is the LTI key/secret unique to an institution, domain, or course?

Our LTI allows you to access the appropriate domain (e.g. courses.lumenlearning.com, ohm.lumenlearning.com) for the particular course.
When you add the External Tool at the Admin/System Level, it allows the course cartridge import to automatically connect and verify access thereby providing a relatively seamless experience for the teacher and student.
The LTI key/secret is unique to the institution, and we want it to match all *.lumenlearning.com domains. D2L requires specific sub-domain entries, so we use the same key/secret for each External Tool.

It depends on the type of course (Waymaker and Lumen OHM = Yes, Candela = No)

The number of cartridges and their need to be unique depends on whether teachers are adopting or adapting (e.g. editing) a course.
Candela courses are generally a ThinCC.
Waymaker courses are delivered as native course cartridges, depending on the LMS (e.g. Brightspace/D2L gets a Brightspace/D2L course file, Blackboard a Blackboard course file, and so it goes...)

Send user ID to tool provider: This is the unique ID we use to determine who the user is across multiple LTI launches.
Send user name to tool provider: The teacher has a dashboard that shows each student's progress and scores and the student's name.
Send user email to tool provider: The teacher can choose to send emails to the students via Waymaker about questions they missed on their quizzes.
Send system username to tool provider: This is not directly used. It is useful in cases of debugging problems since this is usually a human-readable unique identifier for a user.
Send system Org Defined ID to tool provider: We use this for scoping permissions and data to a school.
Send system role to tool provider: Admins, teachers, and students have different interfaces and permissions. We base that on their role in the LMS. If no role is sent we assume they shouldn't have access.