>Isn't the SYS(0) function a solution ?
Unfortunately not a total solution. Users could be using ie: VFP3 and windows 3.1 combination and logging to network w/o netbeui. Or VFP5 and WAN where computer names could be same for two different computers (workgroup differ). And worse sys(0) doesn't always work as intended (ie: for simple test run it on FPDOS 2.x + win95 net - you get empty string just a #). I think TCP/IP address or physical ethernet card address are almost unique values one could get (but how under Win* ? It was easy with DOS and FP 2.x). Of course you could get those for your own computer from registry and use as a unique value. I wonder in case using TCP/IP would wingate, winframe etc would pose a problem (drop me a message if anybody sure it won't).
Also harddisk serial number is only unique by chance and easily can be altered and make all computers in a network have the same value.
Frankly, to me, except TCP/IP and physical ethernet card ids nothing seems unique for a computer (damn those that I could get for only my own computer).
Anyway for a better sys(0) and harddisk serial etc etc take a look at Focus.fll by Pat Boens. You could even use the fll functions instead of substr(), getfile() and to control max number of users logged to your app.
Cetin