/usr/lib/puredata/doc/6.externs/ is in puredata-doc 0.43.0-4.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/puredata/doc/6.externs/0.README.txt
/usr/lib/puredata/doc/6.externs/dspobj~.c
/usr/lib/puredata/doc/6.externs/makefile
/usr/lib/puredata/doc/6.externs/obj1.c
/usr/lib/puredata/doc/6.externs/obj2.c
/usr/lib/puredata/doc/6.externs/obj3.c
/usr/lib/puredata/doc/6.externs/obj4.c
/usr/lib/puredata/doc/6.externs/obj5.c
/usr/lib/puredata/doc/6.externs/test-dspobj~.pd
/usr/lib/puredata/doc/6.externs/test-obj1.pd
/usr/lib/puredata/doc/6.externs/test-obj2.pd
/usr/lib/puredata/doc/6.externs/test-obj3.pd
/usr/lib/puredata/doc/6.externs/test-obj4.pd
/usr/lib/puredata/doc/6.externs/test-obj5.pd