They do have chapters. But IRC sections are unique across all chapters. There is only one Section 12, so chapter is irrelevent in your parent's citation. (If you wanted to be nit-picky, there is no "IRS Code", it's simply IRC or "Internal Revenue Code") IRC is US Code Title 26. There are also subtitles and subchapters, which you failed to mention, and THEN parts.
Specifically, IRC Section 12 is in subtitle A, Chapter 1, subchapter A, Part II. Unfortunately for Ottair, there is no Paragraph 14. There is no other (US) IRC Section 12. And no, I am not a CPA, enrolled agent, or a lawyer (though I play one on TV...), so my citation is probably not written properly, but I can still provide a reference:
http://www.law.cornell.edu/uscode/html/uscode26/usc_sec_26_00000012----000-.html
That is the site to which the IRS links when you look for Internal Revenue Code. Funny how even the IRS doesn't want anything to do with the code.