The rules file to use. The rules file describes how to interpret
the values of the model, layout, variant and options fields.
If NULL or the empty string "", a default value is used.
If the XKB_DEFAULT_RULES environment variable is set, it is used
as the default. Otherwise the system default is used.
The rules file to use. The rules file describes how to interpret the values of the model, layout, variant and options fields.
If NULL or the empty string "", a default value is used. If the XKB_DEFAULT_RULES environment variable is set, it is used as the default. Otherwise the system default is used.