My bad, I was looking at the manual page via Google which apparently got
me an older version of the doco.
It would be nice if the old syntax could still work (at least during a
transition period), but I guess that's squarely an upstream issue.
** Changed in: pdftk (Ubuntu)
Status:
Thanks for your report, era! Please note, that since pdftk 1.45 the syntax has
changed. Shorthands are replaced by the full words [1].
The man pages and the official documentation have been updated, but maybe
something was missed.
Which documentation did you use? The man page on your system (man