Colin Adams wrote:

Gestalt has always allowed this, and no special option is needed (nor can I see why one ought to be needed).

In XSLT 1.0, it was not allowed to have both. The commandline syntax was different for -it and without -it:

I don't think XSLT 1.0 had an option to specify the initial template. An XML input document was required also, and could not be omitted. So compatibility doesn't arise.