It can describe the actual service or project need, while other evidence explains the employee’s knowledge and qualifying employment. Do not treat one letter as proof of every condition.
Keep the claims within the writer’s knowledge
Distinguish what the customer observed from the organization’s internal training and employment facts. Avoid attributing unsupported conclusions to the letter.
Internal design documents, architecture decision records, runbooks and implementation guides naming the employee as author or maintainer, significant incident write-ups, and code ownership records where policy allows sharing them. Ask which examples establish the material facts, and coordinate the employer's technical staff and legal reviewer before submission so the evidence neither overexposes confidential information nor becomes too generic to support the claim. Build a dated review file around training originals, project versions, supervisor confirmations, entity relationship records, and source files showing personal participation. Gather original job descriptions, payroll entries, training certificates, project assignments, product documentation, and manager statements explaining which duties continued after reclassification and which were added. Preserve dated drafts, revision histories, technical notes, project assignments, performance records, and statements from knowledgeable supervisors explaining what the employee created, adapted, or approved.