Zero'es in mbox on lines with date?

[Dennis Bednar]

I noticed that some of the lines in my mbox file, saved by
the "s file" cmd of the S5 /bin/mail program puts binary
zeros in the text file, nearby the time field, as follows
(only the zero's changed to \000 for clarity):

Received: by teddy.LOCAL on Thu, 9 Jan 86 17:08:48 \000\000\000est
	id AA28338; Thu\000\000\000, 9 Jan 86 19:08:02 pst
In-Reply-To: <894 at rlgvax.UU\000\000\000CP>
	id AA16280; Wed, 8 \000\000\000Jan 86 08:33:18 pst

Comments why?
-- 
Dennis Bednar	Computer Consoles Inc.	Reston VA	703-648-3300
{decvax,ihnp4,harpo,allegra}!seismo!rlgvax!dennis	UUCP