how can I link vumat to cohesive elemet

hi,

    recently,i want to write a delamination law using vumat,but coh3d8 element with  a traction-separation has s33,s13,s23.in vumat,stressold(nblock,ndir+nshr),i don't kown if s33 is  correspond to stressold(nblock,3),and if s23 is  correspond to stressold(nblock,5),

   i hope someone can help me.