Internal Revenue Code has nothing to do with what California requires to put for state information on W-2 forms.  

See FTB Pub 1017, page 6, question 17, and page 9, question 47.  They probably have specific instructions on preparing W-2 forms -- someone else can find it.  

https://www.sccgov.org/sites/air/resources/Documents/Contracting/1017.pdf