Terminology: what to call the trunk

[Greg Ward]

Let's see if I've got my history right here:

  * CVS has a formal notion of the trunk: all revisions with two
    components (1.1, 1.2, 1.431) are on the trunk.  But it has no
    way to *name* the trunk; in some contexts, HEAD means "tip of the
    trunk", but that's not reliable.  And it doesn't refer to the
    trunk as a whole, just the tip.

  * Subversion has no formal notion of the trunk, just a strong
    convention that you do your main line of development in a 
    directory called "/trunk".  Likewise /branches and /tags are
    just strong conventions.  As a result, there *is* a reliable way
    to name the trunk, but it's not universal.  If you called it 
    "/mainline" rather than "/trunk", then that's the name you use.

So far I'm on safe ground ... I understand CVS very well and
Subversion pretty well.  Now I'm going out on a limb:

  * Git and Mercurial both have a formal notion of the trunk and a way
    to name it.  In git's case, it's called "master", and in
    Mercurial's case it's called "default".  Regardless, master/default
    is always there and can always be named: "git checkout master" and
    "hg update default" take you back to the trunk.

Is that correct (at least as far as Mercurial is concerned)?  

Or is "default" just the *default* name of the trunk?  I.e. can I
decide that I want to call the trunk "trunk" instead of "default"?

(Rationale: for years, I have been trying to get my CVS-using
colleagues to call the trunk "the trunk": not "HEAD", not
"MAIN_TRUNK".  Now I'm looking at switching from CVS to Mercurial and
spending the next couple of years explaining that "it's spelled
d-e-f-a-u-l-t, but pronounced trunk".  Aieee!  I'd rather it was
called "trunk" from the beginning.)

       Greg