An action whereby the weight of that portion of the drill string below a ram BOP is supported by a tool joint resting on the closed pipe ram or through the use of a special hang-off tool that lands in the wellhead.
Source: API STD 53, Blowout Prevention Equipment Systems for Drilling Wells, Upstream Segment, Fourth Edition, November 2012. Global Standards
Riser when disconnected from seabed. NOTE Hang-off is usually differentiated from disconnected. Disconnected is normally the condition directly after disconnecting the riser. Hang-off is normally associated with the riser suspended from the rotary table.
Source: API RP 17G, Recommended Practice for Completion/Workover Risers, Second Edition, July 2006 (Reaffirmed April 2011). Global Standards