Description of files found in .../NetBSD-1.3.1/i386/binary:

This directory contains the gzip compressed tar files of the NetBSD
binary distribution. The contents of these files are described fully
in the INSTALL document.

The sets/ directory contains the main portion of the distribution. On
most sites, the security/ directory contains the distribution of
security related software. See INSTALL and the numerous
README.export-control files for details.

Every directory contains several checksum files (BSDSUM, CKSUM, MD5, &
SYSVSUM) that contain checksums of all the other files made with the
cksum(1) utility. The MD5 checksums made with "cksum -m" are
considered the "safest", followed by the CKSUM POSIX-style checksums
made with the plain "cksum" command. Please check the integrity of
your distribution against one of these sets of checksums if
possible. The BSDSUM and SYSVSUM files contain checksums made with the
historical BSD and System V checksum utilities and are provided for
those with no other checksum utilities available.