> if used('selhdr.dbf')
> else
> use selhdr in 0 exclu
> endif

Well, an alias can't hold a ".", so I know you'll always hit the else. And it lookslike you're trying to test if a table can be opened exclusivly before you open it? Not possible, what you do is try to open it exclusivly, THEN test its success, if you want, temporarily disable the error hanlder.

lcError = on('error')
on error *

use excl

on error &lcError

Now test if it worked or not.