/usr/share/acl2-6.3/books/system/ is in acl2-books 6.3-5.
This file is owned by root:root, with mode 0o755.
..
/usr/share/acl2-6.3/books/system/compare-out-files.o
/usr/share/acl2-6.3/books/system/convert-normalized-term-to-pairs.o
/usr/share/acl2-6.3/books/system/deps-pcert.o
/usr/share/acl2-6.3/books/system/extend-pathname.o
/usr/share/acl2-6.3/books/system/f-put-global.o
/usr/share/acl2-6.3/books/system/gather-dcls.o
/usr/share/acl2-6.3/books/system/hl-addr-combine.o
/usr/share/acl2-6.3/books/system/legal-variablep.o
/usr/share/acl2-6.3/books/system/meta-extract.o
/usr/share/acl2-6.3/books/system/origin.o
/usr/share/acl2-6.3/books/system/pcert/
/usr/share/acl2-6.3/books/system/pcert/acl2x-pcert-test-1.o
/usr/share/acl2-6.3/books/system/pcert/acl2x-pcert-test-2-include.o
/usr/share/acl2-6.3/books/system/pcert/acl2x-pcert-test-2.o
/usr/share/acl2-6.3/books/system/pcert/elide-test.o
/usr/share/acl2-6.3/books/system/pcert/mid.o
/usr/share/acl2-6.3/books/system/pcert/pkg-test.o
/usr/share/acl2-6.3/books/system/pcert/sub.o
/usr/share/acl2-6.3/books/system/pcert/top.o
/usr/share/acl2-6.3/books/system/pseudo-good-worldp.o
/usr/share/acl2-6.3/books/system/pseudo-termp-lemmas.o
/usr/share/acl2-6.3/books/system/random.o
/usr/share/acl2-6.3/books/system/subcor-var.o
/usr/share/acl2-6.3/books/system/sublis-var.o
/usr/share/acl2-6.3/books/system/subst-expr.o
/usr/share/acl2-6.3/books/system/subst-var.o
/usr/share/acl2-6.3/books/system/too-many-ifs.o
/usr/share/acl2-6.3/books/system/top.o
/usr/share/acl2-6.3/books/system/update-state.o
/usr/share/acl2-6.3/books/system/verified-termination-and-guards.o
/usr/share/acl2-6.3/books/system/worldp-check.o