You can get this sysid from uname -i
It's called the SWID.
I believe it'll be interfaced through getconf (1m) (see the man) uniquely in the future.
The value can be changed and reburned by HP CE's but only in cases of motherboard replacements is this done. The value is stored in stable storage, on the same flash as your pri boot path and rtc info etc.
It is impossible to modify it yourself (licencing problems otherwise) you need what's called the SS_KEY util that is only available to CEs via passwords based on your chassis serial number.
Later,
Bill
It works for me (tm)