**Body: Flexible**Model ElementBody_Flexible defines a flexible body object in MotionSolve.

**Body: Rigid**Model ElementBody_Rigid defines a rigid body object in MotionSolve. This entity has mass and inertia properties.

**Constraint: Coupler**Model ElementCOUPLER defines an algebraic relationship between the degrees of freedom of two or three joints.

**Constraint: CVCV**Model ElementConstraint_CVCV defines higher pair constraint. The constraint consists of a 3D curve fixed on one body rolling and sliding on a 3D curve fixed on a second body. The curves are required to have a unique point of contact and a common tangent at that point of contact.

**Constraint: CVSF**Model ElementConstraint_CVSF defines a higher pair constraint. A curve on one body slides on a surface that is fixed to a second body. The curve is not allowed to lift off the surface.

**Constraint: Gear**Model ElementConstraint_Gear defines a gear constraint between two bodies.

**Constraint: General**Model ElementThe Constraint_General element is used to specify a user defined general constraint.

**Constraint: Joint**Model ElementConstraint_Joint is used to specify an idealized connector between two bodies.

**Constraint: Mate**Model ElementConstraint_MATE is used to specify general mating constraints between geometric primitives.

**Constraint: Primitive**Model ElementConstraint_Jprim is used to remove degrees of freedom between two bodies by specifying conditions in which the relative translational or rotational motion can occur.

**Constraint: PTCV**Model ElementConstraint_PTCV defines a higher pair constraint. A fixed point on one body slides on a curve that is fixed on a second body. The point is not allowed to lift off the curve.

**Constraint: PTdCV**Model ElementThe Constraint_PTdCV element constrains a fixed point on a body to slide along a curve that passes through the origins of a specified set of markers.

**Constraint: PTdSF**Model ElementThe Constraint_PTdSF element constrains a fixed point on a body to slide along a surface that passes through the origins of a specified set of markers.

**Constraint: PTSF**Model ElementConstraint_PTSF defines a higher pair constraint. A fixed point on one body slides on a surface that is fixed on a second body. The point is not allowed to lift off the surface.

**Constraint: SFSF**Model ElementConstraint_SFSF defines a higher pair constraint. The constraint consists of a surface on one body rolling and sliding on a surface on a second body. The surfaces are required to have a unique contact point.

**Constraint: User**Model ElementThe Constraint_UserConstr element is used to specify a user defined constraint. Your constraint equations may involve the configuration as well as velocity of the system.

**Control: Differential Equation**Model ElementControl_Diff defines a single, first order, user-defined differential equation in MotionSolve. A single, dynamic state is associated with the differential equation. This state is integrated along with the rest of the system states.

**Control: FMU**Model ElementFMU (Functional Mock-up Unit) is an abstract modeling entity that defines a generic modeling element in MotionSolve.

**Control: Plant Input**Model ElementThe Control_PlantInput element defines the inputs to a mechanical system or plant.

**Control: Plant Output**Model ElementThe Control_PlantOutput element defines the outputs from a mechanical system or plant.

**Control: SISO**Model ElementControl_SISO is an abstract modeling element that defines a linear, time invariant dynamic system in the Laplace domain. SISO stands for __S__ingle __I__nput __S__ingle __O__utput.

**Control: State Equation**Model ElementControl_StateEqn is an abstract modeling element that defines a generic dynamic system. The dynamic system is characterized by a vector of inputs `u`, a vector of dynamic states `x`, and a vector of outputs `y`. The state vector `x` is defined through a set of differential equations.

**Force: Beam**Model ElementForce_Beam defines a straight, massless beam of uniform cross section acting between two Reference_Markers, `I` and `J` that belong to two different bodies.

**Force: Bushing**Model ElementForce_Bushing defines a linear force and torque acting between two Reference_Markers, `I` and `J`.

**Force: Contact**Model ElementForce_Contact defines a 2D or 3D contact force between two bodies.

**Force: Field**Model ElementForce_Field defines a force and torque acting between two Reference_Markers, `I` and `J`.

**Force: FlexModal**Model ElementForce_FlexModal defines a distributed force on a flexible body.

**Force: Gravity**Model ElementForce_Gravity defines the acceleration due to gravity along the global X, Y, and Z directions.

**Force: Joint Friction****Force: Multi-Point**Model ElementForce_MultiPoint defines a force and torque acting between many Reference_Markers.

**Force: One Body Vector**Model ElementForce_Vector_OneBody defines a general force and/or torque acting one a Reference_Marker.

**Force: Penalty**Model ElementForce_Penalty defines a generalized force whose purpose is to maintain a "soft" constraint in the system.

**Force: PTdSF**Model ElementThe Force_PTdSF element defines a contact force between a deformable surface and point.

**Force: Spring Damper**Model ElementForce_SpringDamper defines a spring damper force acting between two Reference_Markers.

**Force: State Equation**Model ElementForce_StateEqn is an abstract modeling element that combines the modeling capabilities of the Control_StateEqn and the Force_Vector_TwoBody model elements.

**Force: Two Body Scalar**Model ElementForce_Scalar_TwoBody defines a force or torque acting between two Reference_Markers.

**Force: Two Body Vector**Model ElementForce_Vector_TwoBody defines a general force and/or torque acting between two Reference_Markers.

**Joint Initial Velocity: Cylindrical**Model ElementThe JointInitialvel_Cyl element defines the initial velocity for a cylindrical joint element. It allows you to specify the initial velocities for both the translational and the rotational degree of freedom.

**Joint Initial Velocity: Revolute**Model ElementThe Jointlnitialvel_Rev element defines the initial angular velocity for a revolute joint element.

**Joint Initial Velocity: Translational**Model ElementThe JointInitialvel_Trans element defines the initial translational velocity for a translational joint element.

**Messaging**Model ElementThe Messaging element allows you to control how MotionSolve generates messages.

**Motion: Joint Based**Model ElementMotion_Joint defines a motion input at a degree-of-freedom in a joint.

**Motion: Marker Based**Model ElementMotion_Marker defines a motion input between two Reference_Markers.

**Parameters: Linear Solver**Model ElementParam_Linear defines the solution control parameters for a linear analysis. These parameters control the types of linear analyses to be done and the output options.

**Parameters: Simulation**Model ElementParam_Simulation defines the solution control parameters for simulations that are associated with more than one analysis method. Exceptions are noted.

**Parameters: Static Solver**Model ElementDefines the solution control parameters for static and quasi-static analysis, where the parameters control the accuracy of the solution and the method to be used for solution.

**Parameters: Transient Solver**Model ElementParam_Transient defines the simulation control parameters for a time-domain-based nonlinear dynamic analysis.

**Parameters: Units**Model ElementParam_Unit defines the units for the model being defined.

**Point Mass**Model ElementBody_Point defines a point mass entity in MotionSolve.

**Post: Graphic**Model ElementPost_Graphic defines a graphic element that can be used for visualization and also for 3D body contact.

**Post: Output Request**Model ElementPOST_REQUEST defines an output request entity in MotionSolve. POST_REQUESTs are written to MotionSolve output files so that they may be used for plotting and signal processing by HyperGraph and HyperGraph 3D.

**Post: User Output Request**Model ElementThe Post_UserAPI element allows you to generate your own results file. You can only have one Post_UserAPI without an ID. Use Post_UserAPIS to have more than one Post_UserAPI.

**Post: User Outputs Request**Model ElementThe Post_UserAPIS element allows you to generate your own results file. Post_UserAPIS supports more than one Post_UserAPI with an ID.

**Reference: 2DCluster**Model ElementA Reference_2DCluster specifies that a given set of bodies be constrained to move in one of the three principal planes: XY, YZ, or ZX.

**Reference: Array**Model ElementThe Reference_Array model statement specifies a list of variables (which are used by other MotionSolve modeling elements) or constants.

**Reference: Deformable Curve**Model ElementReference_DeformCurve specifies a deformable curve that is made to pass through the origins of a specified set of markers, using CUBIC spline interpolation. These markers may be on separate bodies. As the markers move in space, the curve shape is recalculated using CUBIC spline interpolation, thereby allowing the curve to deform.

**Reference: Deformable Surface**Model ElementReference_DeformSurface element specifies a deformable surface that is made to pass through the origins of a specified set of markers, using CUBIC spline interpolation.

**Reference: Flexible Body Data**Model ElementReference_FlexData contains the condensed representation of the flexibility characteristics of a flexible body. The flexibility data is calculated using a finite element solver, where the complete finite element model is available.

**Reference: FrequencyInput**Model ElementA Reference_FrequencyInput defines the input to the frequency response analysis.

**Reference: Marker**Model ElementA Reference_Marker defines an orthonormal, right-handed coordinate system and reference frame in MotionSolve. A Reference_Marker must belong to a body. The body can be any type: rigid, flexible, or point.

**Reference: Matrix**Model ElementReference_Matrix defines a general, real-valued, M x N matrix for use in MotionSolve.

**Reference: Parametric Curve**Model ElementReference_ParamCurve defines a parametric curve element. A parametric curve is defined in terms of one free parameter, `u`. Referring to the image below, assume a curve C is defined with respect to a coordinate system OXYZ.

**Reference: Parametric Surface**Model ElementReference_ParamSurface defines a parametric surface element. A parametric surface is defined in terms of two free parameters: u and v. Referring to the image below, assume a surface S is defined with respect to a coordinate system OXYZ.

**Reference: PlantState**Model ElementReference_PlantState defines a list of user-defined states used in generating a linear representation of a model about an operating point. The linear representation is used for both eigenvalue analysis and state matrix generation.

**Reference: Solver Variable**Model ElementReference_Variable defines an algebraic state in MotionSolve.

**Reference: Spline**Model ElementReference_Spline defines a spline with one or two independent variables.

**Reference: String**Model ElementReference_String defines a user defined text string in MotionSolve. The string may be of any length. It must contain only printable ASCII characters.

**Sensor: Evaluate**Model ElementA Sensor_Evaluate element is always associated with one or more Sensor_Event modeling elements. When a Sensor_Event becomes "active", a Sensor_Evaluate may be optionally called to define a scalar value based on the current value of the system states. This value is not re-evaluated until one of the parent Sensor_Event's becomes active again.

**Sensor: Event**Model ElementThis model element defines an event sensor in the model.

**Sensor: Proximity**Model ElementThe Sensor_Proximity element defines a sensor that measures the minimum distance between the graphics/mesh of two bodies. The sensor tracks the state of interference of the graphics/mesh, the length of the minimum distance, and the coordinates of a pair of closest points. These quantities can be accessed using the PROXIMITY function for use in defining expressions or for plotting.

**Subsystem: Planar**Model ElementA Subsystem_Planar element aggregates a collection of Reference_2DCluster elements.