I'm recently questioned about the concept of "Depends On"/"Blocks" Links and how they'd be used.
eg. Two WIs are created, A and B.
Relationship being set: A depends on B and B blocks A
I'm with most of people, just instinctively think if we try to close A with B still in open status, then we should be warned or stopped from doing it as B is not completed yet. In fact, that's not the case after I tried quickly. I can close A without any problem and warning.
I did some quick search and here I want to share what I found in this post:

Here are three posts being found about this topic:
https://jazz.net/forums/viewtopic.php?t=20503
https://jazz.net/forums/viewtopic.php?t=21847
https://jazz.net/forums/viewtopic.php?t=2210

As Sharoons mentioned in the first post: "The Depends on and Blocks link is a logical dependency and not a schedule dependency. "

This doc in the info center talking briefly about the Schedule dependencies: http://pic.dhe.ibm.com/infocenter/clmhelp/v3r0m1/topic/com.ibm.team.apt.doc/topics/c_dependencies.html
In the "Finish-to-start dependencies" section:
"You can create finish-to-start dependencies between work items. In these dependencies, the start of the successor work item, depends on the completion of another work item, the predecessor. The successor work item can start only after the predecessor work item is completed."
It looks very close to what most of people would expect how it works.

Please note, we can also get some info from the first post, which is there won't be any warning shown if there's any "depends on" and "blocks" relationship being violated by the scheduler.
Enhancement is opened for it: https://jazz.net/jazz/resource/itemName/com.ibm.team.workitem.WorkItem/151220

Cheers,
Lionel