In the meantime, let me first post what I think is the likely solution for Brain's problem (and thank you for trying out the seemingly underused Physics!).
Joint Type: is either "World" (=0) or "Object" (=1)
You will want the joints that are not affected by gravity to be zero (world). So for a suspension bridge, the joints at each end of the bridge (where the first plank is tied to the cliff edge) would be set to zero for this field, whereas all the plank to plank joints are set to 1.

A few things to keep in mind with physics stuff:

PHYSICS_JOINTS:

Joint entities have a TYPE field. The values can either be 0 or 1. If memory serves me correctly, 1 forces the joint to become RIGID at its assigned position. A value of 0 allows the joint to FALL freely and be affected by gravity or force entities. Make sure that whatever joints your object is supposed to hang from are assigned as RIGID. All others should be assigned as free fallers. ( brain, this is usually a common cause for your problem. )

A joint entity has 2 fields to specify physics objects that it is connected to. If you have a joint that connects two physics objects, you simply specify both objects in the 2 fields. It doesn't matter which is specified first. If you have a joint that connects a single physics object to a static part of your world, such as a chain link to a wooden post, you specify the physics object ( chain link ) in the first field and leave the second field set at NULL. Currently joints only have 2 fields to hook up physics objects. You can't connect a single joint to 3 or more physics objects. A situation like that would require connecting one joint to the first and second object, another joint connecting the second and third object, another joint connecting the third and fourth object, etc...

Each joint entity has a NEXT field that you use to create a consecutive list of joints.

Example- In the NEXT field for JOINT1 you would specify JOINT2. In the NEXT field for JOINT2 you would specify JOINT3. Keep linking joints in this fashion. The NEXT field for the last joint should remain NULL. DO NOT make the list circular. The list should be linear. It IS possible to link joints in any order as long as the list is linear, but I recommend linking in increasing order because they're easier to deal with.

PHYSICS_OBJECTS:

Like physics joints, physics object entities also have a NEXT field. Build your list of physics objects the same way.

Physics objects should be placed at their respective model's center of mass position. Placing the physics object entities at strange positions relative to their respective models can lead to weird/unstable motions at runtime.

A physics object entity has a single field that points to the model that relies on its center of mass position. Be sure to set this properly.

PHYSICAL_SYSTEMS:

The physical system entity contains 2 fields. One field points to the FIRST physics joint in the joint list you created above. The other field points to the FIRST physics object in the object list you created above.

Apologies in advance if you knew this already and if your physics problem is related to something else.

[This message has been edited by Grappleman (edited 07-12-99).]

[This message has been edited by Grappleman (edited 07-12-99).]