I don under stand : a line code : 'sale.mt_order_confirmed': lambda self, cr, uid, obj, ctx=None: obj['state'] in ['manual', 'progress'], : I dont know what is  'sale.mt_order_confirmed' ?

what is 'order_confirm'? what is syntax?

class sale_order(osv.osv):
    _name = "sale.order"
    _inherit = ['mail.thread', 'ir.needaction_mixin']
    _description = "Sales Order"
    _track = {
        'state': {
            'sale.mt_order_confirmed': lambda self, cr, uid, obj, ctx=None: obj['state'] in ['manual', 'progress'],
            'sale.mt_order_sent': lambda self, cr, uid, obj, ctx=None: obj['state'] in ['sent']
        },
    }

 def action_button_confirm(self, cr, uid, ids, context=None):
        assert len(ids) == 1, 'This option should only be used for a single id at a time.'
        wf_service = netsvc.LocalService('workflow')
        wf_service.trg_validate(uid, 'sale.order', ids[0], 'order_confirm', cr)

        # redisplay the record as a sales order
        view_ref = self.pool.get('ir.model.data').get_object_reference(cr, uid, 'sale', 'view_order_form')
        view_id = view_ref and view_ref[1] or False,
        return {
            'type': 'ir.actions.act_window',
            'name': _('Sales Order'),
            'res_model': 'sale.order',
            'res_id': ids[0],
            'view_type': 'form',
            'view_mode': 'form',
            'view_id': view_id,
            'target': 'current',
            'nodestroy': True,
        }

Thanks all.