Which of the following is NOT part of the ProTools session hierarchy?

The correct answer is the Digital Audio Workstation Server because it is not a component of the Pro Tools session hierarchy. In Pro Tools, the session hierarchy includes essential elements that are directly related to how sessions are organized and stored within the application.

Session folders are the main directories that contain all relevant files for a specific project, providing a structured way to manage the different components of a session. Audio files are the actual recordings or sound data that are used within a Pro Tools project, and they are critical for the operation of the software as they contribute to the final mix. WaveCache files are also part of the session structure as they store waveform information for the audio files in a session, ensuring quick access and smooth playback.

In contrast, a Digital Audio Workstation Server is a broader concept that may encompass various digital audio workstation applications and their networked functionalities. It is not specifically tied to the organization of files within Pro Tools sessions, which is why it is excluded from the hierarchy. Understanding these components is essential for managing and navigating Pro Tools effectively.