Table 1: Explanation of terms in (1).

Gravitational interaction force between particle and observer (=3D vector)
Field vectors to arrive at the interaction force vector
Position of particle compared to observer, in direction particle to observer
Velocity and acceleration vectors of particle compared to the observer
Vector norm of and
Velocity of the expansion of gravity in vacuum
( /
Gravitational constant = 6.67 ×  m3 kg−1 s−2
mobs Gravitational mass of the observer
mpart Gravitational mass of the field generating particle
(, )*The dot product and cross product