On Mon, Dec 8, 2014 at 8:18 AM, Steffen Thorsen <thorsen@timeanddate.com> wrote:

The Mexican state of Quintana Roo will likely change to EST in 2015, by not
going back from DST in October 2015. Its a bit unclear if they will still observe
DST the years after.

Some sources in Spanish:
http://sipse.com/novedades/reconocen-el-trabajo-de-empresarios-con-cambio-de-huso-horario-126236.html
http://www.unioncancun.mx/articulo/2014/12/04/medio-ambiente/congreso-aprueba-una-hora-mas-de-sol-en-qroo

The second article cited has another point that affects time zone history. It says,

Con la modificación, se podría terminar con el conflicto horario que existe entre los municipios de Quintana Roo con el municipio de Felipe Carrillo Puerto, mismo que se declaró en rebeldía desde hace 15 años en que fue instaurado un cambio de horario en México y, desde entonces, se ha negado a modificar su huso horario como el resto del país.

My translation:

With this change, the time conflict that has existed between the municipios of Quintana Roo and the municipio of Felipe Carrillo Puerto may come to an end. The latter declared itself in rebellion 15 years ago when a time change was initiated in Mexico, and since then it has refused to change its time zone along with the rest of the country.

Background:

Mexico's primary subdivisions are states, and its secondary subdivisions are municipios. Quintana Roo (QRoo) is the name of both a state and a municipio. The municipio of QRoo is in Yucatán state, not QRoo state. The municipio of Felipe Carrillo Puerto (FCP) is in QRoo state. Therefore, "los municipios de QRoo" probably means the municipios that constitute QRoo state, excluding FCP.

There are several populated places in Mexico named FCP, but only one municipio by that name - the one in QRoo. They are all named for a Mexican statesman. As customary, his last name, Carrillo Puerto, was formed from his father's and mother's patronymics.

According to the tz database, the event that occurred 15 years ago was that QRoo state (America/Cancun) switched from Eastern to Central Time on 1998-08-02, homogenizing it with the rest of the Yucatán peninsula (America/Merida). Both areas have observed DST since 1982.

Conclusion:

If the paragraph is correct and I've understood it correctly, there should be a new zone for FCP municipio, equivalent to America/Cancun until 1998-08-02 and remaining on E%sT after that date. Abbreviating the zone name to fourteen characters or fewer is problematic. America/CarrilloPuerto might be acceptable.

Gwillim Law