Use training records, permitted project summaries and internal role documentation that explain the knowledge accurately, and have the company identify what needs careful handling before anything is submitted.
Choose evidence that answers the actual question
A reviewer needs to understand the process and the individual's role in it, not an unexplained batch of sensitive files. Ask which specific examples establish the material facts, and coordinate with legal counsel on how to present anything genuinely confidential.
Give every technical assertion a source: training history, internal manuals, system access records, project correspondence, and statements from people able to explain the employee’s role. The goal is intelligibility, not volume. Hypothetical example: a museum-lighting systems specialist submits a folder of diagrams with no explanation of which designs the specialist created or maintained. A chronological index and informed declarations would settle that point better than more files. Entity records must also show the qualifying relationship. L-1B requires the relevant continuous foreign employment year within the prior three years and carries a five-year maximum stay.
Ask the technical witness to identify the source material before describing its significance.
That connection is central to the filing.