AGREEMENT (Dec. 23, 1999). The total number of properties that constitute the general railway communication line called Vía Corta del Istmo de Tehuantepec, as well as the buildings and facilities for the provision of auxiliary services, is destined for the service of the Ministry of Communications and Transportation.

ORIGINAL TITLE (Dec. 23, 1999). It is assigned in favor of Ferrocarril del Istmo de Tehuantepec, S.A. of C.V. to: i) operate and exploit the general railway communication road, which corresponds to the road called Via Corta del Istmo de Tehuantepec and which includes the railway, the right-of-way, the traffic control centers and signals for the railway operation.

FIRST MODIFICATION (Dec. 20, 2017). The goods subject to the assignment were modified to read as follows:
I) The general railway communication road, which corresponds to the Trunk Track of the Istmo de Tehuantepec, consisting of:
- The stretch of the Isthmus of Tehuantepec: Medias Aguas, Veracruz to Salina Cruz, Oaxaca.
- The Chiapas section: Ixtepec, Oaxaca to Ciudad Hidalgo, Chiapas.
- The Mayab section: El Chapo, Veracruz to Merida, Yucatan.
- The section of the new road that is constructed from Medias Aguas, Veracruz to Coatzacoalcos, Veracruz.
II) The general railway communication road, which corresponds to the short route Oaxaca, which goes from Sanchez, Puebla to Oaxaca, Oaxaca.

SECOND MODIFICATION (Apr. 20, 2023). The Palenque, Chiapas to Merida, Yucatan railway (FA) and its branches, sections Merida-Tizimin (FD), Empalme Valladolid-Valladolid (FX), Merida-Progreso (FN) and Campeche-Lerma (FL), are excluded from the assignment title, and incorporated entirely to the Maya Train Railway.
Likewise, it is incorporated the provision of public rail freight and passenger transport service through the granting of concessions to third parties when the assignee ceases to have exclusivity rights.

THIRD MODIFICATION (June 07, 2023). It is modified to i) incorporate the operation, exploitation and provision of public service in the segments of the "Z", "ZA" and "FA" that goes from Coatzacoalcos to Medias Aguas, from Hibueras to Minatitlán and from Coatzacoalcos to El Chapo, respectively and goods of public domain and ii) establish rights of way in favor of Ferrosur with respect to the segments that are incorporated.