The author of the Global Sourcebook for International Data Management here. @gHosts - thanks for your comment, it's a fair one. I did write much of the basics 30 years ago - different times - and with over 4200 pages and just one author who does this for love, I do have to concentrate on certain aspects above others. I shall have a look at the gender/sex information throughout and see what I can update - a disclaimer is certainly required, in any case!
I know of someone broadening the traditional "Mr/Mrs/Ms" "M/F" and is unclear on what to broaden it to, nor can find agreement amongst the clients as to what to broaden it to, beyond that they want it broadened.
The former is officially used in GB, but it sees informal use in US media and elsewhere. I live in a country that doesn't use honorifics, but I use 'Mx' where it's required. I'm unsure about non-English equivalents for 'Mx'.
The latter sees use in BE, DE, IS, MT, NL and on job boards in Europe and more progressive areas. It's also seeing use in the US on passports and NY birth certificates.
There are of course others, but none as widely adopted as these.