What must a subpoena commanding attendance at a deposition specify?

The correct answer addresses a fundamental aspect of a subpoena for depositions, which is to provide specific information about how the testimony will be recorded. This is essential because the method of recording can influence the logistics of the deposition and ensure all parties are prepared for that aspect of the process.

In a deposition context, clarity about the recording method helps to ensure that there is a reliable record of the testimony, which is vital for later use in legal proceedings. This could involve specifying whether the testimony will be recorded via video, audio, or stenographic methods, as each has different implications for how the proceedings are conducted.

While location, identity of the witness, and date and time of the deposition are certainly important details that a subpoena must also typically include, the emphasis in this particular question is on the recording method, making it a critical detail for the logistics and management of the deposition itself.