globus_gram_protocol_definition(3) on Linux
The text 54b89b5f0595, as Debian 8 (Jessie) shipped it.
GRAM Protocol Definition The GRAM Protocol is used to handle communication between the Gatekeeper, Job Manager, and GRAM Clients. The protocol is based on a subset of the HTTP/1.1 protocol, with a small set of message types and responses sent as the body of the HTTP requests and responses. This document describes GRAM Protocol version 2.