The rearfoot post can be ground flat or with motion. How it is ground is denoted by a number such as 0/0 or 4/4 where the first number denotes the amount of inversion of the lateral aspect of the post and the second number denotes how much motion is allowed. A 4/4 post is inverted 4 degrees on the lateral aspect and allows 4 degrees of eversion to bring the medial side of the post to the ground. In this case the medial side of the post is ground so that it is parallel with the front edge of the orthosis. For a 0/0 post, the rearfoot post is ground parallel to the front edge of the orthosis.