The letter from Claudius Lysias to Governor Felix follows the common form of a Hellenistic letter (a standard Greek-style letter used in that time). It names the writer and the recipient, gives a greeting, and explains the main issue. However, it does not include a closing farewell (see study note on 15:29).
The letter also summarizes the events leading up to it and explains the actions taken. It shows that the commander believed he had followed proper Roman legal procedures.
His Excellency: This title was often used for people with high social, political, or economic status (Luke 1:3).