From the International Electrotechnical Commission webstore
“IEC 60749-26:2013 establishes the procedure for testing, evaluating and classifying components and microcircuits according to their susceptibility (sensitivity) to damage or degradation by exposure to a defined human body model (HBM) electrostatic discharge (ESD).
The purpose (objective) of this standard is to establish a test method that will replicate HBM failures and provide reliable, repeatable HBM ESD test results from tester to tester, regardless of component type. Repeatable data will allow accurate classifications and comparisons of HBM ESD sensitivity levels. ESD testing of semiconductor devices is selected from this test method, the machine model (MM) test method (see IEC 60749-27) or other ESD test methods in the IEC 60749 series. The HBM and MM test methods produce similar but not identical results; unless otherwise specified, this test method is the one selected.”