The Commands page displays a list of pre-defined commands that you can easily add to toolbars by drag and drop. They mostly come from the default toolbars.
The commands are divided into a number of categories that loosely groups similar commands. You can use the search field at the bottom of the page to search for a command by name or description.
Click a command in the list on the right to see a full description of it underneath, along with information about where it comes from if applicable.
All these commands are built from the internal command set. Of course these commands are not the only ones available in Opus - they're just a starting point. When you select a command from the list the underlying raw command is shown as well.
Drag a command from the list to add it to a toolbar or menu.