NJ Driver's License?

Z – No full air brake equipped CMV.

Note:
Effective November 9, 2015, the “Z” restriction code that had been used to capture a Graduated Driver License (GDL) restriction is now captured using a “T” restriction. All GDLs issued up until that time continue to be valid with their “Z” identifier until their expiration date.

www.nj.gov/mvc/drivertopics/gettingcdl.htm