ASTM International, in conjunction with the Nitinol community, has issued several standards that aid in specifying Nitinol.

ASTM F 2004-05   Standard Test Method for Determination of Transformation Temperature of Nickel-Titanium Shape Memory Alloys by Thermal Analysis

ASTM F 2005-05   Standard Terminology for Nickel-Titanium Shape Memory Alloys

ASTM F 2063-05   Standard Specification for Wrought Nickel-Titanium Shape Memory Alloys for Medical Devices and Surgical Implants

ASTM F 2082-06   Standard Test Method for Determination of Transformation Temperature of Nickel-Titanium Shape Memory Alloys by Bend and Free Recovery
 
ASTM F 2516-07e1   Standard Test Method for Tension Testing of Nickel-Titanium Superelastic Materials