In addition to the databases you have open, ChessDB provides a clipbase database, which is just like any other database except that it exists in memory only and has no files for permanent storage.
The clipbase is useful as a temporary database, for merging the results of searches on more than one database or for treating the results of a search as a separate database.
For example, assume you want to prepare for an opponent and have searched a database so the filter contains only games where the opponent played White. You can copy these games to the clipbase (by dragging from their database to the clipbase in the database switcher window), switch to the clipbase database, and then open the Tree window to examine that players repertoire.
Note that you can copy games in the filter of one database directly to another opened database (without needing the clipbase as an intermediary location) using the database switcher window.
Note that the clipbase cannot be closed; selecting the [File: Close] command while in the clipbase is equivalent to [Edit: Reset Clipbase] which empties the clipbase.
The clipbase has a limit of 20,000 games at any time, since it exists in memory only.