var billSearch = search.create({
                type: search.Type.VENDOR_BILL,
                filters: [
                    { name: 'statusRef', operator: 'is', values: ['open'] },
                    { name: 'approvalstatus', operator: 'is', values: ['2'] }
                ],
                columns: [
                    { name: 'usertotal' }
                ]
            })

for example fails with:

An nlobjSearchColumn contains an invalid column, or is not in proper syntax: usertotal.

but based on https://system.na1.netsuite.com/help/helpcenter/en_US/srbrowser/Browser2016_1/script/record/vendorbill.html that field should exist