how to get the UFSID of a mounted filesystem ?

[Pete French]

I observer that when I mount a UFS filesystem using the device
name then the entry vanishes from /dev/ufsid, and glabel list no longer
shows the device. Which begs the question, how do I find
out the ufsid of a mountde filesystem (e.g. '/' so that I can change it's
fstab entry for the next reboot?)

Am slightly embarassed to have to ask for help! Am sure this was
easy and in dmesg last time I did this...

-pete.