Different types of coupling

A co-worker of mine (the one and only Dan Robinson) sent around an email to our team talking about different types of coupling between systems.  I'll post the bullet points here:

• Afferent – who calls this system?  A system with high afferent coupling is hard to replace
• Efferent – who does this system call?  A system with high efferent coupling has a lot of dependencies
• Platform – do both systems have to be on the same platform?  Levels of interoperability…
• Spatial – how much do systems know about each other’s location?  If the topology changes, do things break?
• Temporal – how much do things wait for each other?  If one system slows down, how are other systems affected?

I know this is a quick post but I feel better knowing that I got it out there.  I don't know about you but this is one I will keep coming back to.