In ear marking, a crop, slit, split, or bob of the cow's ear is made with the penknife blade, and portions of the ear are removed or cut according to the established precedent in the brand book. Like the iron itself, ear mark styles and wattles are considered a rancher's property and can be used by other ranchers only if purchased and duly recorded with the state brand inspector's office. Ear marks and wattles are efficient identification methods in foul weather, under dusty conditions, or when cows are bunched up together. The law requires marking cattle with branding irons, and the customary legal system based on traditional usage since the middle of the nineteenth century calls for ear notching and wattling. All ranchers brand cattle, and most ranchers brand their horses too.
Some ranchers also ear mark and wattle their cattle.
There are conventions in brand choice and design based on practicality and economy. Thinner irons would slice through the hide and injure the animal, and wider irons would dull the design. A plain design further reduces the blotching problem. The best iron designs are simply but ingeniously created to represent the owner's ranch or name. Running irons are kept by ranchers and used to mark strays when necessary, or to put a neighbor's brand on his strays that drift into the wrong herd.