31.6. The first vice-chairman replaces the chairman if the latter is absent or unable to act or if the office of chairman is vacant.
The second vice-chairman replaces the first vice-chairman if the latter is absent or unable to act or if the office of first vice-chairman is vacant.
The replacement of one office holder by another does not constitute the holding of offices concurrently.
A substitute mayor who, pursuant to the third paragraph of section 29, replaces a mayor as a member of the Council does not replace the mayor as either the chairman or the vice-chairman.