why can the distance only be set on a phy not a dev

[David Goodenough <david.goodenough@btconnect.com>]

Using the iw command, most things can either be directed to a dev or
a phy, but a distance can only be set on a phy.

This leads to problems as I do not know which phy is connected to a 
dev (or at least I do not know how to find out which phy is connected
to a dev), and so in my Debian /etc/network/interfaces file I have:-

iface wlan0 inet manual
	pre-up iw dev wlan0 interface add mesh0 type mp

iface mesh0 inet static
    address 10.101.11.254
    netmask 255.255.255.0
    pre-up iw dev mesh0 set channel 153
    post-up iw phy phy0 set distance 3500
    up iw dev mesh0 mesh join MeshId

so in the mesh0 stanza I have a reference to phy0 which is hard
coded and if it changes subject to error.

So either I need to be able to set distance to dev mesh0, or have
some means or working out which phy corresponds to dev mesh0.

Any ideas?

David