$self->conv_usage("password for database access needed")unless($self->conv_support->param("pass"));
$self->conv_usage("can only do conversion to ensembl OR Vega, not both")if($self->conv_support->param('do_vega_sc')&&$self->conv_support->param('do_ens_sc'));
$self->conv_usage("You need to do vega->veg or ensembl->vega conversion")unless($self->conv_support->param('do_vega_sc')||$self->conv_support->param('do_ens_sc'));