The answer is simple but we decided to have Irma from the CRT Certification Control department provide the definitions located in the Tequila STANDARD NOM-006-SCFI-2012.
Below are the Tequila classes as defined by the Tequila Standard…
 
5.2 Classes
5.2.1 Based on the characteristics acquired in post-distillation processes, Tequila is classified into one of the following classes:
• Blanco o Plata.
• Joven u Oro.
• Reposado.
• Añejo.
• Extra añejo.

The definitions are located in paragraphs 4.36.1, 4.36.2, 4.36.3, 4.36.4, and 4.36.5. of Tequila STANDARD NOM-006-SCFI-2012, Liquor Tequila-Specifications
 
5.2.2 For the international market the classification can replace the previous paragraph with the corresponding language translation according to the regulation of marketing country or place, or, for the following:
• “Silver” instead of Blanco or Plata.
• “Gold” instead of Joven or Oro
• “Aged” instead of Reposado.
• “Extra aged” instead of Añejo.
• “Ultra aged” instead of Extra añejo.