Defines the type of perforation mechanisms. A device that uses shaped explosive charges to perforate wells in preparation for production. The use of shaped explosive charges to create perforation tunnels. The explosive charge produces an extremely high-pressure jet that penetrates the casing or liner. An interval treated with acid based hydraulic fracturing. An interval treated with hydraulic fracturing. The uncased portion of a well. An interval where communication tunnels have been created from the casing or liner into the reservoir formation. The value is not known. This value should not be used in normal situations. All reasonable attempts should be made to determine the appropriate value. Use of this value may result in rejection in some situations.