Suryananda ,

Is one's response to the invitation one's word, as in a contractual obligation or future manifestation of expression of intent?

The response may be either or a combination of both. It is more like what you can do rather than what you say you will do or you want to do. It depends on the power to resist based on actions during the life of the physical body. It hinges on obligations which one did not complete or which one completed with attachment.