A marker is the local coordinate system included in a body. Most of entities in a model are defined with the markers. Therefore, when making an entity such as a joint, a force, a contact, and so on, the markers are generated automatically. Additionally, the user can make a marker using the Marker icon in the Body group, and it is possible to modify the position and the orientation of the generated marker in the Marker property page.
The marker has three axes which are distinguished as the colors such as Blue (X-axis), Red (Y-axis), and Yellow (Z-axis) as shown below.
Figure 1 Marker
Figure 2 Marker icon of the Marker and Body group in the Professional tab