Additional strong evidence is provided by Sect. 4 of (Roscoe 1999A) Table 1 there shows that the pre-hole cutting values of act, with near certainty, as noisy traces of optical radii. Similarly, Table 2 there shows how the post-hole cutting values of also act, with similar near certainty, as noisy traces of optical radii. Since the optical radii themselves are very likely dependent upon bulge radii, then a natural conclusion is that the pre-hole cutting and post-hole cutting values of provide estimates of the boundaries of bulge radii effects.
In other words, there is good evidence to support the conclusion that the two values of provide estimates to the interior and exterior boundaries of physically coherent transition regions between bulge-dominated and disc-dominated dynamics.
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