BrainStorm has three basic entry icons - a single embossed line represents an entry with no descendants, a double embossed line (with a green highlight) shows that it has descendants, and a dot embossed on the surface means that this is not really an entry at all, just a place marker for the end of the list.
When selected, the entry icons are darkened and the active entry icon gains an up facing triangle to remind you that if clicked on with the mouse, it will be 'promoted' to the header entry, revealing its descendants.
If the selected entry is in the heading area, the arrow will point downwards to show that it can be 'demoted' to the body of the display.
If the entry is being edited, the icon colour changes to pink
BrainStorm uses other icons to signify different conditions:
A 'namesake' is an entry which is identical to one or more others. They all share the same descendants (if any). Or you can prevent an entry being part of a namesake chain, by disabling it either before or after it happens.
One entry in the model can be 'marked'. This gives a source or a destination for the Throw and Retrieve commands, and a destination for the Jump command.
Finally, you may protect an entry from accidental tampering by making it 'Read only'.