This is a variation of the "human readable files" argument. So once
again I claim that no such thing exists other than printed listings
(which then are not machine readable, at least not much in practice).

The image file is our source: the preferred form for editing programs.
It is far nicer when coupled with the .sources and .changes files, of
course, but we can get by without these. You do need the proper
application for dealing with the image - the VM.

Now we can dump out the image as a huge XML file and we should have no
problems reading that back in. We can also develop a more refined system
like the Transporter tool in Self. But would the result be human
readable? Only in the sense that it could be printed and a person could
read it over the phone to some other person. Nobody would understand it
(unless it was a trivial "3+4" image) nor want to make any changes to it
in this format. So I would argue that this would not be a "source file"
by any reasonable definition even if it did play nice with cvs and vi.
And having pointed text editors to my share of .sources and .changes
files from various Smalltalk I would argue that these aren't quite
sources for Squeak either (though they are from GNU Smalltalk and Little
Smalltalk).

Our sources are the .image files. It isn't what people are used to, but
that doesn't make it less true.

-- Jecel