Entities must be often selected during editing. They can be selected by left mouse click or using option to select all entities in world or sector. They can be also selected using volume selection, by pressing 'V'. Volume is a virtual box placed anywhere in the world. It can be aligned to viewing area using key 'A'. You can also invoke select entities dialog using 'N' or 'Ctrl+Shift+A' which will list all entities from world or entities contained with volume box. Dialog will allow you to sort entities using class, name, id number or position. 'RMB' on certain entity property (i.e. class) will remove all entities from list that don't have same property value. 'Shift+RMB' will remove all entities that do have same property value. 'LMBx2' will close dialog and select clicked entity. 'Feed volume' operation will put selected entities into volume. That way they can be circled using '[ ' and ']' ' keys.