This is a PPWIZARD command line switch.
This is an alternative way of specifying an input mask and will protect you from some uses of Unix "special" characters.
Unix tries to expand anything on the command line which is not obviously a switch (starts with '-'), so for example, if you pass "*.it" on the Unix command line ppwizard might see "a.it", "b.it" and "subdir\c.it". If you pass "-input:*.it" then ppwizard will see "*.it" and process it accordingly (so it will not process "subdir\c.it").
The error messages when Unix (not all) tries to expand something that is not valid can be confusing as some Unixes add the current directory to the "invalid" file.