TinPusher,
Part of the problem is that ICAO procedures are very generic and never go into the level of detail which States tend to publish for their specific operation. Their advice on reclearances tends to cover changes to flight plans, destinations, etc. There is nothing I can find on the scenario we are discussing. Also looking in the ICAO documents for phraseology terms, there is no ICAO phrase such as that suggested by Buffy, the only vertical reclearance phrases are 'Stop climb/descent' or 'Recleared'.
Both the UK and US procedures are quite specific however, and that is that all restrictions for a particular element (level, speed, time or route) are cancelled in a reclearance of the same element.
In Sink Rates example the descent clearance to FL140 is a reclearance, replacing the original clearance which was FL180 level by ABCDE. The fact the original FL180 was given as a restriction doesn't change the fact it
is a clearance whether stated explicitly by ATC or as part of a published SID/STAR on which the aircraft has been cleared (these types of routes are just documented ATC clearances after all).
Unfortunately I don't follow your logic on restrictions I'm afraid. I apologise if I've misunderstood. What you seem to say is that if the aircraft has a restriction A (lets call it FL180 by ABCDE) and is then given a reclearance to FL140 with no restriction stated, then you still expect the pilot to comply with restriction A. Yet if he is given restriction A, but instead of a free descent is given a descent to FL140 level by VWXYZ (i.e. restriction B), you would only expect restriction B to be complied with. What's the difference such that restriction A is assumed to be cancelled in one case but not the other ?
In the UK and the USA, there should be no doubt. The controller is required to reiterate the restriction if they want it to apply. Now, what many people do in my experience is to monitor the profile being followed and issue the reclearance when it is obvious that the aircraft is going to make the restriction anyway. So we do not physically reiterate the restriction, but manage the traffic profile so that it complies anyway. This echoes what identnospeed says.
I think your last point will very much depend on what the STAR chart says. For the UK, the published levels are for guidance. If the controller wants the pilot to comply with them then they have to pass that as part of the clearance. It would not be good enough for us to simply clear the pilot to FL180 and then expect them to cross ABCDE at that level as per the chart, because that is not what we have cleared the pilot to do. Other countries may have different procedures and have 'hard' altitudes on the chart. In those cases what I have heard is the pilot being cleared to follow the STAR 'with the profile'. No descent clearance is passed and the pilot is expected to follow the route both laterally and vertically.
As to why have STARs ?, again from a UK viewpoint, the prime purpose is so we know where the aircraft are going to fly laterally. The vertical elements are enshrined in ATC procedures such as Standing Agreements between sectors or airfields so when it's busy the profile will be followed by the clearances issued, rather than the pilot being cleared to follow the profile on their own. However these vertical profiles, which are often not ideal in economy terms, are relaxed when traffic permits. In fact sometimes in the quieter periods the controller will be working both the sectors for which the profile has been designed (for ATC co-ordination purposes). So unless they have a split personality (mmmmm, in ATC that is quite possible !!), the restriction can be lifted and usually is, saving the crews a couple of Kg of fuel.
I agree with you that speed restrictions should be adhered to, but that is because the controller has generally not varied or lifted them. In the examples we are talking about the levels have been varied by ATC, thus overriding any restrictions.
Now we've got Grandad Flyers attention, I hope this lot doesn't scramble their brain too much
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