Buld icon and content assit in Eclipse pages?

Question

Sometimes a little bulb icon appears in the current edit field in Eclipse. Hint says "Content Assist Available".

What does this bulb mean?

(P.S. I would not ask if Ctrl-Space invoked some content assistance)

Answer 1

It is supposed to mean that content assist is available. However as you have found it does not seem to function on this field in the extension point editor.