1.) The National Association of Chain Manufacturers (NACM) defines Overhead Lifting in the Welded Steel Chain Specifications, §3.4:
http://www.jrclancy.com/Downloads/TrimChains-ESG.pdf
Also from J.R. Clancy.
http://www.jrclancy.com/Downloads/ChainforTheatricalUse.pdf
See also J.R. Clancy's stand on the definition and use of the various terms, over head lifting and the suitability of different chain products for theatrical use.That process of lifting that would elevate a freely suspended load to such a position that dropping the load would present a possibility of bodily injury or property damage.
http://www.jrclancy.com/Downloads/TrimChains-ESG.pdf
Also from J.R. Clancy.
http://www.jrclancy.com/Downloads/ChainforTheatricalUse.pdf