Who determines the title of an initiative?

Federal Law on Popular Referendum (March 14, 2014)

Article 14. Citizens who wish to file a request for popular referendum for the next immediate referendum day should submit a Notice of Intent to the Chairman of the Executive Board of the corresponding Chamber with the corresponding format defined by said Chamber for such purpose. […]

Article 15. The format to obtain signatures will be determined by the Chambers of the Congress of the Union, previous consultation to the Institute, meeting the requirements provided by this Law and that should contain at least:

I. The national significance raised topic;

II. The question proposal;

III. The folio number of each page;

IV. The name, signature, voting key or id number of the back of the voting card from the optical character recognition (OCR) of the valid voting card with photo, and

V. The date of issue.