For the Engineer profession it is the baccalaureate or the provincial licence, either of which satisfies the rule. Scientific Technician/Technologist has no diploma-plus-support shortcut: the applicant must show theoretical knowledge in an enumerated scientific or engineering discipline, the ability to solve practical problems in that discipline or apply its principles to basic or applied research, and work in direct support of a professional in one of those disciplines.
Match the credential to the exact profession first
The TN list attaches a distinct qualification to each occupation, so the review begins by naming the occupation the duties actually fall under and then reading its rule. Hypothetical example: a Boischatel structural engineer who holds both an OIQ licence and a baccalaureate in civil engineering satisfies the Engineer rule twice over; the file should simply present both. A technologist with a three-year DEC and a decade of field inspection experience cannot use Engineer, and must instead show that the Scientific Technician/Technologist conditions are met, including work in direct support of a professional in an accepted discipline.
Citizenship sits beside the credential: the applicant must be a Canadian or Mexican citizen, and a permanent-resident card does not substitute. Prearranged employment with an identified U.S. employer completes the picture; a plan to look for work after arrival is not a TN case at all.
Anyone holding shares in the hiring company must have that interest examined against the self-employment bar before the letter is drafted.