The commissioning procedure, training and certification records, installation logs, a comparison with other technicians, and the sales contracts for the U.S. installations. Marketing brochures and generic job descriptions add little.
Use the company's own working documents, in their working form
Hypothetical example: the company keeps its commissioning steps in a shared document that has been revised eleven times, with the applicant listed as author on six revisions. That document, with its revision history, is stronger than any polished statement written for the petition. Add the internal training curriculum, records of sessions he led for newer technicians, the log of Canadian sites he commissioned with dates, and service tickets showing him resolving faults others escalated. Include a short, signed statement from the engineering lead explaining why the U.S. installations need this person rather than a locally hired electrician. From the corporate side, provide share registers or filings proving the affiliate relationship and evidence both entities are operating. The petitioner files Form I-129 with the L supplement and pays the fees on the USCIS schedule. Confidential material can be marked as such; it does not need to be omitted.
Hypothetical example: a seating-systems manufacturer gives its proposed transferee a generic letter saying she is an expert in quality. That conclusion does not show what the knowledge is or how it was gained. Build a document set around a particular company process: controlled work instructions, training completion, version history, examples of internal troubleshooting, and a U.S. duty list tied to that process. Protect confidential material with sensible redactions while preserving enough substance to be assessed. An opening file audit should assemble a cross-reference from each claimed knowledge area to a record. If the U.S. role could be filled after routine orientation, say less about tenure and more honestly about the limits of the position; unsupported claims of rarity invite questions rather than resolving them.