Fuel injectors and Installing on fuel rail

The writing on the side of the injectors does it mean
anything wen installing new ones had to do head gaskets
and I bought a kit for it now I'm back at the injectors but I
notice the writing on the one side like w and p   5 under the
w where the plug in is on the  injector and the other ones
are  w and c   7   under it. And just w  and o beside each
other little confused or does it make a difference. Please
and thank you for any help I can get. My email is
Cory.white200@gmail.com please email me with