Vkasav lah - not on a beheimah , and it says "Sefer" Sefer is not fit for eating and an animal is living a Sefer isn't.
In the time prior to paper currency Vkasav lah... you can't physically write on a coin, and Sefer Korsah and nothing else.
Now the Rabanan say Korsah there can't be any chronic condition that binds her to him....but there are many halachas as we know from gittin. That even with zero conditions... bpanai nechtav, written lshma if not it's not a Sefer krisus...etc...
Avrahom Kevelson, United States
If the husband writes "you are permitted to marry anyone apart from such and such" this is not a Get because there is still some connection between the couple (see Gemara Gitin 82a) but otherwise as long as he wrote the Get specially for his wife this is kosher because it is Lishmah.
Wishing you a Kesivah vaChasimah Tovah
Dovid Bloom