Please read the following table in Markdown format and then answer the question according to the table. Table cells in one row are seperated by '|', and different rows are seperated by '
'.

Table:
| Team | Outgoing manager | Manner of departure | Date of vacancy | Replaced by | Date of appointment |
| --- | --- | --- | --- | --- | --- |
| Dundee United | Tommy McLean | Mutual consent | 4 September 1997 | Paul Sturrock | 5 September 1997 |
| St. Johnstone | Paul Sturrock | Resigned | 5 September 1997 | Sandy Clark | 7 September 1997 |
| Motherwell | Harri Kampman | Resigned | 15 October 1997 | Billy Davies | 15 October 1997 |
| Aberdeen | Alex Miller | Sacked | 8 December 1997 | Paul Hegarty (Caretaker) | 8 December 1997 |
| Dunfermline Athletic | Bert Paton | Resigned | 5 January 1998 | Dick Campbell (Caretaker) | 5 January 1998 |
| Rangers | Walter Smith | Resigned | May 1998 | Dick Advocaat | June 1998 |
| Celtic | Wim Jansen | Resigned | May 1998 | Jozef Vengloš | June 1998 |
Question:
What is the Date of vacancy for Tommy McLean?
Answer:
4 September 1997