2023-08-31/28 I don't think that's valid, as the abbreviated form allows excluding identical parts, so expanded this is 2023-08-31/2023-08-28 which has the

2023-08-31/28 I don't think that's valid, as the abbreviated form allows excluding identical parts, so expanded this is 2023-08-31/2023-08-28 which has the start time after the end.