Actually, the index displays information or full board diagrams for all the games in the current file.

Note that:

• this is a standard feature of the Smart Game Format to enable files with several games inside, although a lot of collections happen to be with only one game per file. For this reason...
• next version (2.20, alpha under testing, see related topic in this discuss page) enables to open a folder and apply all commands to it (including index, printing, problems, and so on)

Gilles