Document return codes of 'svn ls'

Hello,

How can I know if a file is not present in specific revision?

From one side I can run 'svn ls' and if it returns 0 when file exists,
but if 'svn ls' returns 1 it is impossible to guess between generic
error and situation when path for file doesn't exist in this specific
revision. Message parsing seems unreliable, because messages seem to
depend on locale. Everything could be fine if return codes allowed
recognizing these conditions. Perhaps there is some other way. Any
hints?

--
anatoly t.