AIS uses the C-RTL to write its output.
The C-RTL by default makes a new file inherit the RMS attributes of an existing file with the same name.

We all have seen NAV_UTIL EXTRACT MACHINE output right?
Something like...

<?xml version='1.0' encoding='ISO-8859-1'?>
<navobj version='5.3.3.5'>
<machine>

Now watch this:

$ create test.txt
$ nav_util export machine test.txt
$ type /page test.txt
<
?
x
m
l


v
e
r
s

Why?
Well NAV_UTIL puts out a single character at the time to print the output, interspersed with an occasional NEWLINE.
That works fine with a STREAM_LF file which the DEC CRTL creates by default.
But that CREATE command created a Variable length record file with implies newline for each record.
That attribute was inherited by the file create for the NAV_UTIL output.
Now every character put will become a whole record and the implied newline takes care of the rest.
So now you know.

btw... this also explains why writing certain log files can be very slow: each character can become an RMS call.

Cheers,
Hein.