new anthropometric indicators: (1) lightness , (2) height-to-mass ratio

[kliegl]

This is a feature request. Would it be possible to provide age- and sex-adjusted z-scores and percentiles also for:

(1) lightness = 1 / weight (2) height-to-mass ratio = height/weight ?

Reason: I would like to replace the transformations used in this paper with age-/sex-adjusted z-scores. https://www.researchgate.net/publication/377692841_Impact_of_Height-to-Mass_Ratio_on_Physical_Fitness_of_German_Third-Grade_Children.

Thank you.