Cloth Belt
Let's think about what an actual belt does for real-world clothing before moving on. When pants are belted, they stay attached to the person no matter where he moves. With a digital character the principle is the same so attaching the cloth to the character needs to be handled a little differently than just fixing the points. Fixing the points will just keep the points in a single fixed position. What belting does is attach specified points to a specified deformed polygon object. This allows for the cloth to stay attached to the deformed points of the character at a definable distance.
This may come in handy is to go from a T-pose of a character to its start pose of the animation. If the animation starts the character off in an extreme pose, belting all points of the garments to the character's geometry will aid in getting the garments into position for the extreme pose. After the garments have been properly simulated into position, defining this position as its Initial State in the Dresser tab will allow the simulation to start from this position or state.
Cloth Belt tags only work in combination with polygonal objects. Note also that Cloth Belt tags are not designed to connect objects to which Cloth tags have been assigned or to connect splines; this is what the Connector tag can be used for.
Animating Belt Objects
The Belt On text box on the Dresser tab has the ability to be animated, meaning that multiple Cloth Belt objects can be used to influence the same piece of cloth. The problem with this is that the belted points that are defined with the Set button can't be animated; however, vertex maps can be animated to achieve this same type of effect.
To do this you will first need to belt all points that will be influenced by any Cloth Belt object. Using the Live Selection or new Brush tool, paint the points that need to be influenced by the first Cloth Belt object with 100% weight. Another vertex map will need to be created for the points that will be influenced to the second Cloth Belt object. Drag & drop the first vertex map into the Influence text box on the Effects tab and set a keyframe for this tex box using the gray dot.
Record a keyframe when the change between the two Cloth Belt objects occurs by Ctrl+clicking on the gray dot next to the Cloth Belt text box. At this same frame, you need to switch from the first vertex map to the second one by dragging and dropping it into the text box. Ctrl+click the gray dot to create a keyframe for this change.