I want to connect to a network share without being too particular about the credentials, but @DEFAULT doesn't appear to be a valid constant. It didn't turn blue, nor does it work.
@NONE is no good either.
@DEFAULT and @NONE did not get highlighted in blue for me either, but they worked when trying to map a shared (with everyone) folder on a server to a drive letter.
@DEFAULT and @NONE are extender constants and extender constants are not necessarily added to WBS's context highlighting system but they are both supported by and work with the extender. The OP's problem has some other cause than the constants not working.
Thank you for clearing that up. I'll see what I can figure out.
As usual, this was the result of me doing something stupid. I was passing \\Server\Share as the share. Once I trimmed it down to just the share name, it worked. I simply jumped to a conclusion when my constants didn't change blue.