6.2.4   - See yo/history.yo
6.2.2   - See yo/history.yo
6.2.0   - See yo/history.yo
6.1.3(-pre)   Repaired several textual imperfections and delete -> delete []
          where new [] was used.
6.1.2. This file was defined to summarize intermediate modifications.
        - description of ios condition flags refined
        - description of string::getline() refined.
        - open_mode `creat' changed into `trunc' (reading and writing streams)

6.1.1b Minor textual modifications since 6.1.0