Which of the following documents is required to prove attended training not listed in official documents?

The required document to prove attended training not listed in official documents is typically training certificates. Training certificates serve as formal evidence that an individual has completed specific training sessions or programs. They provide a verifiable record that includes the details of the training, such as the subject, duration, and the organization that delivered it. This form of documentation is recognized and accepted for substantiating claims about training not found in official records.

While service school documentation, personal essays, and course syllabi may offer some context about a person's training or education, they do not equate to the direct proof of completed training in the same way as training certificates do. Service school documentation usually refers to official educational campaigns or advanced training recognized at a higher level, and personal essays are subjective and not standard proof of training completion. Course syllabi outline the content of a course but do not demonstrate individual attendance or completion.