Meaning of size of /dev/pts/ files

[rockyhotas%firemail.cc@localhost]

Hello!

The /dev/pts/ files seem to have each their own size, as if they were
regular files. First curious fact: `ls -l' doesn't show the size in
bytes of such files (for some reason).

crw--w----  1 rockyhotas     tty  5, 129 Sep 24 21:44 129
crw--w----  1 rockyhotas     tty  5, 154 Sep 25 07:27 154
crw--w----  1 rockyhotas     tty  5, 160 Sep 25 07:24 160
crw--w----  1 rockyhotas     tty  5, 174 Sep 24 21:14 174
crw--w----  1 rockyhotas     tty  5, 175 Sep 25 07:27 175

(columns are: permissions, number of hard links, user owner, group 
owner,
major number, minor number, last modified date, filename)

Instead, `exa' shows their sizes:

crw--w----  5,174 rockyhotas    24 Sep 21:14  174
crw--w----  5,129 rockyhotas    24 Sep 21:44  129
crw--w----  5,160 rockyhotas    25 Sep 07:24  160
crw--w----  5,175 rockyhotas    25 Sep 07:27  175
crw--w----  5,154 rockyhotas    25 Sep 07:27  154

(columns are: permissions, size, user owner, last modified date, 
filename)

In this case, /dev/pts/129 and /dev/pts/174 have the same number of
characters printed in the stdout: despite this, their files have 
different
sizes. So, second curious fact: the sizes of these pts files are not
related to the number of characters received by them as output of some
command.

pts files also seem to have different sizes in FreeBSD and Linux. Also, 
in
Linux there is a manpage pts(4) for pts devices (where anyway sizes are
not mentioned), while I couldn't find a similar page in NetBSD.

Any clue about what these sizes actually represent?

Rocky