Hi, Ed,
The end of the arrow shaft is slotted, the arrow head put into the slot, and then animal sinew was wrapped around
the shaft around the shaft, arrowhead and between the notches you mentioned on the arrow head.
Images can be seen here of Primitive Arrow heads such as the native Americans used.
https://images.search.yahoo.com/search/images;_ylt=A0LEVwtmdEBTnwoA8gNXNyoA;_ylu=X3oDMTB0Yjkwb3VoBHNlYwNzYwRjb2xvA2JmMQR2dGlkA1ZJUDM3MF8x?_adv_prop=image&fr=yfp-t-244-s&va=primitive+arrows
God Bless! Spirithorse