A mark (even one made with a pen); a brand (specifically the brand burned onto the skin of an animal by a government office).
A bookmark or anything used to mark a trail such as a chipped tree, a broken branch, something stuck in the ground can be called a malka. In the branding of animals only the official mark or seal from a government office is called malka, a private branding is called a malka indan.
My carabao has already a brand.