Internal process documentation Marcus authored or substantially contributed to, training records showing how the knowledge was acquired, and a detailed supervisor letter comparing his knowledge with general industry practice, rather than only his job title or tenure.
Show the comparison, not just the résumé
A résumé establishes experience but not specialization. Ask the supervisor to write specifically about what a newly hired industry engineer without Marcus's background would be unable to do, and how long it would take that person to reach an equivalent level. Keep the description concrete and tied to the actual calibration process rather than generic praise.
Collect records that explain the knowledge, not merely the employee’s importance. Useful material can include internal training paths, product manuals not generally available, implementation histories, project records, peer comparisons, and statements from knowledgeable managers. Pair those with payroll and HR records establishing the qualifying overseas employment and ownership records establishing the organizational link. Hypothetical example: An artisan chocolate production technologist has years of experience, but the only draft evidence says she is “exceptional.” A process map showing her role in the company’s proprietary tempering protocol is much more informative. Documents should be dated, attributed, and consistent with the U.S. job description. If customer-site work is expected, include the service agreement and supervision structure so the employer can show who controls the work and why the assignment is not simply supplying labour.
Retain a short explanation for every confidential or technical attachment, including who prepared it and why it is relevant. A reviewer should be able to understand the claimed knowledge without receiving a pile of unexplained manuals, screenshots, or proprietary presentations.