Unicode categories

John C Klensin wrote:
> the view that, at the time, the Unicode
> classifications of characters were considered a little soft

FYI, I asked about Unicode category stability on the Unicode list, and 
received the following info:

From: "Andrew C. West" <[email protected]>

According to my calculations, the number of characters which changed 
their General Category from one version of Unicode to the next is :

1.1.5 -> 2.0.14 = 474 (1.384%)
2.0.14 -> 2.1.2 = 1 (0.0025%)
2.1.2 -> 2.1.5 = 16 (0.0410%)
2.1.5 -> 2.1.8 = 18 (0.0462%)
2.1.8 -> 2.1.9 = 3 (0.0077%)
2.1.9 -> 3.0.0 = 85 (0.2182%)
3.0.0 -> 3.0.1 = 0 (0%)
3.0.1 -> 3.1.0 = 3 (0.0061%)
3.1.0 -> 3.2.0 = 7 (0.0074%)
3.2.0 -> 4.0.0 = 16 (0.0168%)
4.0.0 -> 4.0.1 = 1 (0.0010%)
4.0.1 -> 4.1.0 = 12 (0.0124%)

I don't know what this tells you about the stability of the UCD data though.