Before revision:  The quantiles weighting structure is parsimoniously parameterized by means of a Beta  function whose coefficients are optimized by minimizing a joint VaR and ES loss function of the Fissler-Ziegel class.
After revision:  The quantiles weighting structure is parsimoniously parameterized by means of a Beta weight function whose coefficients are optimized by minimizing a joint VaR and ES loss function of the Fissler-Ziegel class.