OCP Data Center Spec: Ladder Tray

Hi NANOG, The Open Compute Project "OCP" had, at least that I can recall but now can not find, a ladder tray deployment spec in the data center working group. It called for tray to span the middle of the aisle as I remember it. Anyone recall or have a pointer to it? My favorite search engine and the OCP wiki yields nothing. I was also hoping to find someone involved in the spec to discuss a related NFPA issue with. Best, -M<