Ed-

>>>save a little effort - FULLPATH(CURDIR()) will return the current directory properly prefixed without the ambiguity that I've seen arise from using SYS(5) on UNCs where you're working in an unmapped UNC, and terminates cleanly with the \ in all cases.

Great point on using FULLPATH. But, in trying to make sure I understand _all_ your points in this, I find there seems to be no difference between:

?fullpath(curdir())
?fullpath(sys(5)+sys(2003))