Record identifier of LinkageData. It stores a list of forces that acting on the mechanism. Forces are stored as {{str1,vec},{str2,pointofAttack}} sublist
Forces are defined with two vectors. The first one specifies the magnitude and orientation of the force, while the second one specifies the point of attack.
str1 is the full name of the link,whose LLRF is the coordinate's frame, where the force vector (vec) is defined .
vec 3 dimensional vector defining the force vector.
str2 is the full name of the link,whose LLRF is the coordinate's frame, where the point of attack vector (pointofAttack) is defined.
pointofAttack 3 dimensional vector defining the point of attack of the force.