Import TMX into new TM, different sub-language | I also need to change the sublanguages, cannot find code for "Spanish international sort"

Forum: SDL Trados support
Topic: Import TMX into new TM, different sub-language
Poster: Yazmin Osoyo
Post title: I also need to change the sublanguages, cannot find code for "Spanish international sort"

I'm trying to implement this sublanguage change method on a very big EN-US to "Spanish International Sort" TM, now I want it to work for EN-GB to ES-MX
However, I cannot find the ISO code for the Spanish International Sort sublanguage, and I can't identify it in the exported TM file.
I would really appreciate your help with this.

[Edited at 2013-08-09 01:23 GMT]