I can create an annex remote named 'test:/test'. git itself does not allow colons in names, though. The name scheme for an annex should be the same as for git repos themselves.

> What do you mean by "an annex remote"? git-annex uses the same
> remotes configuration as does git. If you put invalid
> stuff in .git/config it might handle it slightly different than 
> git, I don't know. Examples needed. --[[Joey]] 

>> What I mean is this:

    % cd 1
    % git init
    % git annex init "my:colon"
    % [...]
    % cd ../2
    % git init
    % git annex init "second"
    % git remote add "my:colon" ../1
    fatal: 'my:colon' is not a valid remote name

>> -- RichiH

>>> I see.. Git annex init does not specifiy a remote's name, it specifies
>>> an arbitrary human-readable description of the repository, which will
>>> be displayed when there is no configured remote corresponding to the
>>> repository. So this is not a bug unless some documentation of that is
>>> unclear. --[[Joey]] 

>>>> Nobody spoke up to say it's unclear, so closing as PEBKAC :)
>>>> [[done]] --[[Joey]] 

>>>>> I still think git-annex should follow the same rules as git in this regard, but if your design decision is different, I won't try to argue the point :) -- RichiH