How to use /gps/hist/type biase?

SPENVIS has an option output particle spectra with a bias towards higher energies so that not only the most likely particle energies are simulated.
This is done with the command

“/gps/hist/type biase”

But I don’t understand how it works and cannot find any documentation about it.
Does anyone know where I can read more about the details of specific commands and parameters like this one?
Or can someone explain to me in detail what exactly this command does and how to use it?
How do I renormalise the results afterwards to get the actual total dose?
How do I account for the bias in the analysis of the simulation output?