  Developments on various relations among stellar variables such as the main
sequence empirical mass-luminosity (MLR), mass-radius (MRR) and mass-effective
temperature (MTR) relations were reviewed. Conceptual changes in their
understanding and usages were discussed. After its discovery, MLR was treated
as one of the fundamental secrets of the cosmos. Differences between
fundamental laws and statistical relations were used to understand long-term
developments of MLR, MRR and MTR. Developments show a break point, initiated by
Andersen et al. (1991), in the line of progress. Before the break when reliable
data were limited, MLR and MRR were calibrated using M, L, and R of binary
components of all kinds visual, spectroscopic, and eclipsing for two purposes:
i) obtaining mean mass, mean luminosity, and mean radius, ii) to estimate M and
R of single stars. By the time of the break, the number of solutions from
detached double-lined eclipsing binaries (DDEB) giving accurate M and R within
a few percent levels are increased. Parameters from very close, semi-detached,
and contact binaries were excluded for refinement, however, MLR and MRR
diagrams were found insufficient to derive MLR and MRR functions because the
dispersions are not only due to random observational errors but also due to
chemical composition and age differences. Then, a new trend was adopted by
replacing classical MLR and MRR with empirical M and R predicting relations.
Thus, the purpose one was suppressed also because the new trend found a
fruitful application in determining M and R of exoplanet hosting single stars.
Corrections on misnames and devising new classical MLR, MRR, and MTR, giving
mean values are encouraged since they are still useful and needed by
astrophysical models requiring such mean values, not only beneficial to
astrophysics, but also beneficial to Galactic, extragalactic search, even
cosmological models.
