IK solutions and their order

Hello,
I am using IKFast for a 7dof robot and I notice that the order of the solutions somehow always correspond to the different posture/configuration(elbow up/down, etc).
Is this due to the method used by the solver that the solutions follow that order? I am able to observe this for quite some time and would like to know if it is always the case and also the reasoning behind this.

Thank you 