Demonstration of the transformation from Galactocentric coordinates to tail coordinates. The black dot represents the globular cluster, while the thick black line shows a segment of its orbit. The star symbol indicates a star particle. The red vector points from the nearest point on the cluster’s orbit to the star particle. The Galactocentric position vector is the y^′-axis. The local orbital plane, the cross-product between the orbit’s local position and velocity vector, defines the z^′-axis. We project the red vector on each of these axes. We measure the x’ coordinate as the path length along the orbit from the cluster to the nearest point. Positive x^′, y^′, z^′ indicate that a star is ahead of the cluster, farther from the Galactic center, and above the orbital plane, respectively.