/usr/share/postgresql/9.5/extension/isn.control is in postgresql-contrib-9.5 9.5.2-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 | # isn extension
comment = 'data types for international product numbering standards'
default_version = '1.0'
module_pathname = '$libdir/isn'
relocatable = true
|