/usr/share/acl2-6.3/books/regex/regex-chartrans.o is in acl2-books 6.3-5.
This file is owned by root:root, with mode 0o777.
It is a symlink to /usr/share/acl2-6.3/books/regex/../../../../lib/acl2-6.3/books/regex/regex-chartrans.o