/usr/share/man/man1/isqlw-vt.1.gz is in virtuoso-opensource-6.1-bin 6.1.6+repack-0ubuntu3.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/man/man1/ISQL-VT.1.gz
/usr/share/man/man1/ISQL-VT.1.gz