LET'S be clear on this.

Educational examinations are calculated to be a specific test, not just about the extent and depth of a student's knowledge but of their ability to communicate that on the day.

You can make a perfectly good case for this being a bad system and that some form of continuous assessment is a superior system, but for as long as traditional examinations exist they have to be about performance on the day, perhaps a flawed test but a rigorous one.

It was therefore decided by a wide consensus that the appeals system for Scottish exams had to change because they were becoming not a case for exceptional external circumstances such as illness or bereavement, but a general get out of jail card for poor performance on the day. Performance on the day is the whole point, harsh but true.

Once the floodgates were opened to the broader argument that Jamie or Kirsty were really very able students but had simply failed to perform on the day, the system was bound to flounder. There was widespread agreement within the system, and no political dissent from without, that limiting the scope of appeals was needed and a fee should be the mechanism.

But now we get the toxic statistic that after the introduction of cash charges for exam appeals the number from private schools have fallen by 36% while those from local authority schools have dropped by 76%.

The Herald shares the concern, but not the politically knee-jerk response demonstrated by Labour yesterday given that they did not object when the system was introduced to end the burgeoning appeals system which was costing £750,000 a year to the Scottish Qualifications Authority.

Further, no-one fully understands what the figures mean. For a start, there are several school sectors in Scotland; the private schools, the state schools in the more affluent areas who feel they compete with the private sector, the schools in smaller towns and burghs who feel above that fray, and other urban schools who are variously flourishing or struggling.

Private schools have always maximised their success in the exams system. It is their unique selling point, and they will pay for appeals more readily, especially if they can pass on the cost to parents.

At this stage the statistics tell us little about the success of appeals, merely the raw numbers. For all we know, private schools may simply be pouring more money into unsuccessful appeals, although we suspect not.

Appeals come on two grounds - the wrong adding up of the sections of an exam, which should surely incur no cost, and the broader claim that the marking was flawed.

Larry Flanagan of the Educational Institute of Scotland argues that the key must always be a genuine belief, based on the professional judgement of teachers, that there is a strong chance of the appeal being successful.

How we get to that happy place when our private and state schools are in market competition is not explained.

He also states: "All pupils should have an equal chance to potentially lodge an appeal, and teachers should be free to consider each request for an appeal to be submitted free of external pressure from any source."

That is hard to argue with, but we have to accept that when it comes to exams some must be allowed to have a bad day.