  The young sigma Orionis cluster in the Orion Belt is an incomparable site for
studying the formation and evolution of high-mass, solar-like, and low-mass
stars, brown dwarfs, and substellar objects below the deuterium burning mass
limit. The first version of the Mayrit catalogue was a thorough data
compilation of cluster members and candidates, which is regularly used by many
authors of different disciplines. I show two new applications of the catalogue
and advance preliminar results on very wide binarity and the initial mass
function from 18 to 0.035 Msol in sigma Orionis. The making-up of a new version
of the Mayrit catalogue with additional useful data is in progress.
