If I understand correctly, these notches hold the blade in a jig as it is being ground.
I believe the notch is to facilitate even sharpening of the edge.
Interesting. I’ve often wondered what that G*******d, stupid, annoying little f****** notch was for..... I had thought it was there for the annoyance and inconvenience of the user.
I use my knifes extensively at work for cutting heavy strapping, sheets of hessian etc and as I try and slide the blade under the material it binds up in that little notch every time.(actually cut myself good because of it once). Every knife I use that had this notch has had an appointment with my dremmel tool or a bench grinder to get rid of it, and I will avoid buying knives with them now........stupid notch