Unfortunately my mail connection broke down for a few hours shortly after I posted my proposal, so I missed most of the replies in my mail. I am now replying based on the archive, but this means it is difficult to quote your messages.
Robbie: that is a good point. In my design I anticipated that one would not want to route a smaller network than a /24, but in fact that could happen in the AMPRnet. The reason I put the 44 in the AS number is to reduce the probability that an AS would collide with another private AS allocated using a different system. However, it of course uses precious space. See below.
Marius: that is interesting. This is exactly the kind of response I hoped for, as I prefer to use a method that is already established rather than inventing my own. I found it appealing that the subnet address can be seen and recognized, these E.212 codes are obscure to me (but probably not to the person who invented this method). This method leaves 5 digits within the country range, which allows for smaller subnets as Robbie proposed. I see one problem: because there is no 1:1 mapping between E.212 code and AMPRnet /16 subnet, it will not always be possible to directly number the AS from the subnet. For typical European countries it will work well, but for the USA there is a "problem" because there are many more /16 subnets allocated to them than there are E.212 codes. Of course there are still more than enough AS numbers, but it means they need to use some registry instead of a direct derivation of the number.
Pedja: as mentioned early in the message, these AS are not for use on the public internet but only on our private radio network. Gateways between radio and internet are supposed not to be running BGP across them, or to filter the private AS and send out the routing under their public AS. That is already happening.
It looks like I will modify the system to look like this for our local use (and others are welcome to follow it: 42eeexxxyy where eee is the E.212 code, xxx is the third octet of the IP address, and yy is a local sequence number 00-99 in cases where multiple AS exist in that subnet. So for 44.137.40.0/22 it will be 4220404000 (204 is the E.212 code for the Netherlands which has 44.137.0.0/16) When I would want an AS for my personal subnet 44.137.41.96/28 it could be 4220404096 or some other arbitrary 42204040xx number. (for now, we only route to the regional subnets level)
In my opinion, it is less easy to read than the first proposal, but of course it has the advantage of more AS space within the local area, and the fact that it is already established in some places. That is an important advantage.
Rob