It turns out the information is indeed on the Azerbaijan Ministry of Foreign Affairs website, just the link does not stand out well and the page contains at least one other broken link.
The countries applying the visa-free regime page has a section
II group.
For the holders of any kind of passports
(Diplomatic, service, (official/special) and ordinary)
Mutual visa-free regime is applied between the Republic of Azerbaijan and countries listed below for
1. National of both countries holding any kind of valid passport –including diplomatic, service (official/service) or ordinary passports providing the right of international cross-border;
2. Family members (supposes and children) of above mentioned persons:
- traveling with them;
- having no personal passports;
- photos, given name, family name and patronymic officially registered
in relevant type of passports
3. stateless persons holding relevant identity document providing the right of international cross-border and granted especially to the stateless persons by the relevant state bodies of the Azerbaijan Republic or appropriate foreign country;
4. Nationals or stateless persons holding Reentry Certificate - temporary document for international cross border, granted only for returning to the citizenship country or permanent residence country in the cases of lost/theft/became invalid/expiry of passport.
The heading of this section is in fact a link, which I missed. It links to a PDF which was Updated: 21.10.2010 and contains:
No Name of the country The allowed duration for staying in
the territory of both countries
without visa
1 Belarus 90 days
2 China 30 days
3 Georgia 90 days
4 Kazakhstan 90 days
5 Kyrgyzstan 90 days
6 Moldova 90 days
7 Mongolia 90 days
8 Russia 90 days
9 Tajikistan 90 days
10 Ukraine 90 day
11 Uzbekistan 90 days
UPDATE
Despite all this evidence, my friend who was on the Tbilisi-Baku train was not permitted by the Georgian customs and immigration people to leave at this border crossing, despite him having printouts of the information I listed above!
If anybody can suggest why this occurred it might well make a better answer! \-:
