A good example of an illustration could be found in the book, "Keris Jawa: antara Mistik dan Nalar", page 157. It shows the 5 major forms.. luk hemet-hemet, luk kemba, luk sarpa lumaku, luk keker/sarpa nglangi and luk rengkol. Of course there are variants in between.
Btw, welcome to the forum.
