The soul is dyed the color of its thoughts. Think only on those things that are in line with your principles and can bear the light of day. The content of your character is your choice. Day by day, what you do is who you become. Your integrity is your destiny - it is the light that guides your way. - Heraclitus
Frankly, my advice is to not worry all that much about what type of relationship it actually is. For example, one poster said that with composition you always delete the part but not with association or aggregation. Many people would disagree with that, and say that you would automatically do that as well for aggregation too. The point is that different people have different styles of working, so if you choose to impart meaning into what the diamonds represent then everyone on the team had better agree to a common set of modeling style guidelines.