The Project Items list is constructed of 3 components:

The line number serves as a placeholder so it is easy to identify each line. 

The checkbox in the Project Items list has two possible states, checked or unchecked.  If the checkbox is unchecked, the Project Item will not be included in the execution of the project.  It will be skipped and all the Action Items in it will be skipped.  To change the checkbox double click on it. 

The Name can be maximum 30 characters long.  

To create a new Project Item, press the Insert key on the keyboard or right click with the mouse to bring up the popup menu and select "Add Item" from the menu.  This will insert the new item below the currently selected item. 

To change the name, select it and press the Enter key on the keyboard or press the F2 key on the keyboard.  You can also double click the name with the mouse to change it.  Right click and select "Change Item" from the popup menu is yet another way to edit the Project Item.

Deleting a Project Item will also delete ALL of it's Action Items.  To limit the risk of accidentally deleting a Project Item, the Build Automator prompts you for confirmation before deleting.  To delete a Project Item, you can use the Delete key on the keyboard or right click and select "Delete Item" from the popup menu.

There are no limits to how many Project Items can be in a single project. 

Items can be moved up and down in the list by using Ctrl-Up arrow and Ctrl-Down arrow on the keyboard or by right clicking on the items list and using "Move Up" or "Move Down" 

Properties for the Project Item can be access by right clicking and selecting "Properties" from the popup menu.

A condition can be enforced on the Project Item and if the condition is not met, the Project Item and all of the Action items will be skipped during execution.  Example of a condition could be:
 
%COPYLATESTBUTTON%=$BUTTON_YES$

When a condition is applied, the checkbox in front of the Project Item changes, see line 5 in the screenshot of the list above.