/usr/share/man/man3/ is in libnutclient-dev 2.7.4-5.
This file is owned by root:root, with mode 0o755.
..
/usr/share/man/man3/libnutclient.3.gz
/usr/share/man/man3/libnutclient_commands.3.gz
/usr/share/man/man3/libnutclient_devices.3.gz
/usr/share/man/man3/libnutclient_general.3.gz
/usr/share/man/man3/libnutclient_misc.3.gz
/usr/share/man/man3/libnutclient_tcp.3.gz
/usr/share/man/man3/libnutclient_variables.3.gz
/usr/share/man/man3/nutclient_authenticate.3.gz
/usr/share/man/man3/nutclient_destroy.3.gz
/usr/share/man/man3/nutclient_device_forced_shutdown.3.gz
/usr/share/man/man3/nutclient_device_login.3.gz
/usr/share/man/man3/nutclient_device_master.3.gz
/usr/share/man/man3/nutclient_execute_device_command.3.gz
/usr/share/man/man3/nutclient_get_device_command_description.3.gz
/usr/share/man/man3/nutclient_get_device_commands.3.gz
/usr/share/man/man3/nutclient_get_device_description.3.gz
/usr/share/man/man3/nutclient_get_device_num_logins.3.gz
/usr/share/man/man3/nutclient_get_device_rw_variables.3.gz
/usr/share/man/man3/nutclient_get_device_variable_description.3.gz
/usr/share/man/man3/nutclient_get_device_variable_values.3.gz
/usr/share/man/man3/nutclient_get_device_variables.3.gz
/usr/share/man/man3/nutclient_get_devices.3.gz
/usr/share/man/man3/nutclient_has_device.3.gz
/usr/share/man/man3/nutclient_has_device_command.3.gz
/usr/share/man/man3/nutclient_has_device_variable.3.gz
/usr/share/man/man3/nutclient_logout.3.gz
/usr/share/man/man3/nutclient_set_device_variable_value.3.gz
/usr/share/man/man3/nutclient_set_device_variable_values.3.gz
/usr/share/man/man3/nutclient_tcp_create_client.3.gz
/usr/share/man/man3/nutclient_tcp_disconnect.3.gz
/usr/share/man/man3/nutclient_tcp_get_timeout.3.gz
/usr/share/man/man3/nutclient_tcp_is_connected.3.gz
/usr/share/man/man3/nutclient_tcp_reconnect.3.gz
/usr/share/man/man3/nutclient_tcp_set_timeout.3.gz