In addition to the common commands, the contextual menu of library configurations in the Library Explorer window contains following commands:
Active Configuration
Marks selected configuration as active.
The search for a fragment file when opening or regenerating the document begins in the active library configuration. If the element is not found, the search continues in all the rest of open configurations.
If several library configurations are open then one of those is the active one, with the icon outlined in red.
Save
Saves the changes in the current library configuration.
Save As
Saves the current library configuration in a new file.
Close
Closes the current library configuration.
Alternative file names
The command is used when you want to rename a file in the library and save links of the file with already existing assemblies. You should specify new and alternative names of the file in the command dialog.
Assemblies will use the alternative name to search for the file, so it should match the old name.