Thanks Amir.

In a broader scope that is more-or-less what I was asking and certificates can be fitted in at a lower level. I need to find out more about Competencies, but the very word pretty well sums up what we're after:

People in a job role need to be competent in certain things, they need proof/validation and this needs periodic renewal. An important point in that thread is that this must be user-centred i.e. on the day that a user completes required training the system must register that after a certain period from that date the competency must be renewed by that user.