  Absolute parameters of 509 main-sequence stars selected from the components
of detached-eclipsing spectroscopic binaries in the Solar neighbourhood are
used to study mass-luminosity, mass-radius and mass-effective temperature
relations (MLR, MRR and MTR). The MLR function is found better if expressed by
a six-piece classical MLR ($L \propto M^{\alpha}$) rather than a fifth or a
sixth degree polynomial within the mass range of $0.179\leq M/M_{\odot}\leq
31$. The break points separating the mass-ranges with classical MLR do not
appear to us to be arbitrary. Instead, the data indicate abrupt changes along
the mass axis in the mean energy generation per unit of stellar mass. Unlike
the MLR function, the MRR and MTR functions cannot be determined over the full
range of masses. A single piece MRR function is calibrated from the radii of
stars with $M\leq1.5M_{\odot}$, while a second single piece MTR function is
found for stars with $M>1.5M_{\odot}$. The missing part of the MRR is computed
from the MLR and MTR, while the missing part of the MTR is computed from the
MLR and MRR. As a result, we have interrelated MLR, MRR and MTR, which are
useful in determining the typical absolute physical parameters of main-sequence
stars of given masses. These functions are also useful to estimate typical
absolute physical parameters from typical $T_{eff}$ values. Thus, we were able
to estimate the typical absolute physical parameters of main-sequence stars
observed in the Sejong Open Cluster survey, based on that survey's published
values for $T_{eff}$. Since typical absolute physical parameters of main
sequence stars cannot normally be determined in such photometric surveys, the
interrelated functions are shown to be useful to compute such missing
parameters from similar surveys.
