Identification should include a selection from the following, taken directly from the EPA's Ozone Layer Protection—Regulatory Programs:

High pressure methods should include the following:

Recovering liquid at beginning of recovery process speeds up process
Other methods for speeding recovery (chilling recovery vessel, heating appliance or vessel from which refrigerant is being recovered)
Methods for reducing cross-contamination and emissions when recovery or recycling machine is used with a new refrigerant
Need to wait a few minutes after reaching required recovery vacuum to see if system pressure rises (indicating that there is still liquid refrigerant in the system or in the oil)

Low pressure methods should include the following:

Recovering liquid at beginning of recovery process speeds up process
Need to recover vapor in addition to liquid
Need to heat oil to 130 degrees Fahrenheit before removing it to minimize refrigerant release
Need to circulate or remove water from chiller during refrigerant evacuation to prevent freezing
High-pressure cut-out level of recovery devices used with low-pressure appliances

High pressure requirements are variable depending on

disposal needs
major vs. non-major repairs
leaky vs. non-leaky appliances
appliance (or component) containing less vs. more than 200 pounds
recovery/recycling equipment built before vs. after November 15, 1993
definition of major and non-major repairs
prohibition on using system-dependent recovery equipment on systems containing more than 15 pounds of refrigerant.

Low pressure requirements include all of the high pressure variables except for the last bullet, with the addition of

allowable methods for pressurizing a low-pressure system for a non-major repair (controlled hot water and system heating/pressurization device such as Prevac)
the need to wait a few minutes after reaching required recovery vacuum to see if system pressure rises (indicating that there is still liquid refrigerant in the system or in the oil).

Process/Skill Questions:

Who certifies recovery equipment?
How often should the filter be changed on the recovery machine?
What can minimize the loss of oil from a refrigeration unit when recovering refrigerant?