~0 is the top of the directory stack, always the same as $PWD. If the characters following the tilde in the tilde-prefix consist of a number N, optionally prefixed by a '+' or a '-', the tilde-prefix is replaced with the corresponding element from the directory stack, as it would be displayed by the 'dirs' builtin invoked with the characters following tilde in the tilde-prefix as an argument (*note The Directory Stack::). If the tilde-prefix, sans the tilde, consists of a number without a leading '+' or '-', '+' is assumed.
-- Andreas Schwab, sch...@linux-m68k.org GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510 2552 DF73 E780 A9DA AEC1 "And now for something completely different."