Italics for foreign words on translations

I'm currently translating the frozen chapters of the book to spanish and I have a little notation issue. In several texts written in spanish, italics is used to indicate that a word comes from a foreign language. For example:

A cookie is used to store informacion on the user's web browser.
Una cookie es utilizada para almacenar información en el navegador web del usuario.

However, the book also uses italics to emphasize certain words when is pertinent. I discussed this matter with @steveklabnik and he told me to submit an issue, because it's important to mantain consistency between languages.

One possible solution would be to translate every word into spanish. However there are some cases where this might be a problem:

• When there is not a precise translation: the word "string" has no direct translation into spanish, the accepted translation would be "cadena de caracteres" which roughly means "character chain". Nevertheless we just say "string" instead of "cadena de caracteres"

• When the translation makes a translation senseless: Saying something like "io stands for input/output" could be translated into "io significa entrada/salida", but now it is not clear why is there an I and an O on io.

Start by reviewing the frozen Spanish chapters and the existing uses of italics for emphasis and foreign words. Compare the examples in this issue across the translations, then document and apply a consistent convention once the treatment of terms such as “cookie,” “string,” and “io” is decided.