strings one after the other in c : "...""...", as if they were concatenate

strings one after the other in c : "...""...", as if they were concatenate

I work on a c code that was not written by me, and there is lots of
fprintf calls like this :
fprintf(file, "blabla1""blabla2%s""blabla3", mystring);
I had never seen that we could put several strings in the second argument
of fprintf, is this a sort of concatenation ? Or is this a feature of
fprintf ? If so, the specification of fprintf does not mention it ?