The Default Origin is always at the center of the Poser scene (coordinates x=0, y=0, z=0). If the default position of a prop is some distance away from the center of the scene, and you use the Default Origin as center of rotation, the prop will orbit the center of the scene at a maybe large radius, like the earth orbits the sun. The "default position of the prop" means the position of the geometry stored in the geometry data (that is the vertex coordinates). You can see the default position, when all channels of the prop are at default value (1 for the scales, zero for other channels). The Translate channels ("xTran" etc.) move the prop along the x, y, z axes of the scene. The Tran channels are evaluated according to the script execution order. The Tran channels are usually placed after the Rotate channels in the code. So, Poser first evaluates the rotations, and then moves the prop to the values found in the Tran channels. Because of this, the standard translations carry the prop and the origin. The center of rotation seems to move with the prop. When you set for example a zRotate channel and the xTran channel of the arrow, the prop and the center of rotation move along the x axis. In the script execution order, Poser evaluates the Rotate channels, before the prop is displaced. Therefore, the Rotate channels apply rotations to the geometry at default position. Once the rotation is evaluated, the geometry including the modified orientation is moved to the new x position, the value of the xTran channel. Then the scene is rendered. You could say the Tran channels in this configuration move the prop including the origins (the Poser Origin and the Default Origin). So, a more accurate answer to the above question is: The Default Origin of a prop is at the center of the Poser scene, as long as all subsequent tran channels are zero. BTW, the Tran channels can be placed right before or after the closing OffsetB channels. In the standard prop code, the Tran channels are placed before the OffsetB block. In the standard figure code, the Tran channels of the actors are placed after the OffsetB block.