Does the immigration cap fit?
The tiny tweak to the immigration rules announced today by the Home Office is not a cap. It's not even a knotted handkerchief.
Officials stress it is simply an "interim measure" and, they've admitted to me, it may have no effect whatsoever on total immigration.
What it does do, however, is illustrate just how difficult it is going to be to introduce an immigration limit next year that has any meaningful effect on the big numbers without damaging an already struggling British economy.
Latest immigration figures show that, in 2008, 590,000 people came to live in Britain.
Today's change only applies to one narrow category and reduces the number by 1,300 over the next nine months. It doesn't cover other categories, which might even increase.
The internal difficulties experienced by the Home Secretary Theresa May in getting even this modest reduction agreed by her cabinet colleagues reflects the lack of room for manoeuvre she has.
Ms May says she is determined to introduce the promised cap because she wants net immigration into the UK to fall to the levels of the 1990s - "to tens of thousands rather than hundreds of thousands".
This is likely to happen even if she does nothing at all. Net immigration in 2008 the latest yearly figure, was 163,000 for the UK and 135,000 for England and Wales. Since then, there have been much tougher rules on non-EU immigration which have significantly reduced numbers arriving and EU migration is falling too as a result of the recession.
I wouldn't be the least surprised if the net immigration figure for 2009 falls to well below 100,000 on the basis of economic and bureaucratic changes last year. No doubt, government ministers will claim credit if this comes to pass.
Nevertheless, we now have a period of 12 weeks consultation in which the details of a cap will be worked out.
Let's be clear: this is a limit only on skilled and highly-skilled workers from outside the European Union coming to live and work in the UK. It won't affect workers from Eastern Europe or anywhere else inside the EU because they, like the British, have freedom of movement.
Roughly 55,000 non-EU workers were given permission to come to Britain to live and work in 2009. Around a third of them came in under the highly-skilled-migrant route - so-called Tier 1.
Two-thirds were skilled workers with a designated job offer in a sector where officials have agreed there is a shortage of suitable applicants in the UK - so-called Tier 2.
In setting the "interim measure" today, the Home Office exempted quite a few of the sub-categories within tiers 1 and 2.
Wealthy investors and entrepreneurs will be unaffected, as will be elite sports-people, ministers of religion and intra-company transfers. Numbers in these categories might conceivably go up over the next nine months.
The reason given for the exemptions is that the measure was simply being introduced to stop a rush of applicants from "speculative" migrants ahead of the cap next year. The restrictions may also reflect pressure from other government ministers and senior Conservatives who are known to have been worried that the changes might damage the economy.
London Mayor Boris Johnson told Channel 4 News that "a crude cap could be very detrimental to the free movement of the talented, creative and enterprising people who have enabled London to be such a dominant global force."
Business Secretary Vince Cable has said that "the process of operating this cap will be subject to consultation, and the business groups will make the point, which I fully support, that if you've got a growing economy you've got to draw people in from all over the world where they've got unique contributions. The new regime has got to accommodate those concerns."
So where to draw the line?
Q: Should a 40-year-old manager earning £54,000 a year in his homeland with a masters degree in business studies and perfect English be allowed to come to work in Britain?
A:This applicant would fail under the current points system.
Q: What about a young graduate, again with perfect English and already earning £34,000 a year in his homeland?
A: This applicant would also fail under the current points system.
So, if the cap is to go further than the current system, it means preventing people coming to Britain who have rare talents and earning potential even greater than these examples.
Some believe that a cap will encourage firms to train British employees for the top jobs. Others argue that these are just the kind of people the UK cannot afford to turn away as it seeks to rebuild its battered economy.
PS I have updated the net immigration figure quoted to reflect both the UK and England and Wales.