John R, points in complex analysis are lines, because the complex plane is fundamentally two-dimensional. A complex number, a ib, that describes a point of the complex plane, has real and imaginary parts. So dimensionless points native to the real line appear as lines native to the complex plane.
" ... does substitution involve a transform of some sort or is it simply an assumed condition (mathematic) which eliminates singularity by virtue of the argument that two points can be infinitely close yet remain a real length?"
Yes to the latter, and that's essentially what makes the complex Hilbert space suitable for quantum mechanics. Because quantum mechanics is founded on empirical phenomena (2-slit experiment) there is no way for singularities (defined as space collapsed to a point) to manifest -- the choice of space forbids it.
"Thanks for any elaboration. jrc"
No, John -- thank you, for asking real questions instead of making nonsense claims and saying, "that's math," when it ain't.