Based on the provided texts, what is the complete protocol for arriving at and departing from Shirdi, and what specific role does Udi play in this process?

The process of visiting and leaving Shirdi is entirely governed by Sai Baba's will. Chapter 35 clearly states Baba's saying, 'No one comes unless I bring them,' and 'Without my wish, who will leave the doorstep?' This indicates that both arrival and departure require his grace. The protocol for leaving is particularly detailed. A devotee must not leave on their own whim, as this invites obstacles. Instead, one must formally ask for permission by bowing to Sai. The culmination of this request is the receipt of Udi. As verse 156 clarifies, the blessing given along with the Udi constitutes the permission to leave. Therefore, the Udi serves as the final, tangible confirmation of Baba's consent for a devotee's departure.