Why are 'sec-' and 'tert-' prefixes printed in italics? While reading about nomenclature of branched alkyl groups, I read that certain common names are also approved by IUPAC. Among those names, only few prefixes are italicised (namely sec- and tert-) and others like iso and neo are printed normally. These names are documented in the IUPAC blue book. What can be the reason for italicising sec- and tert- and leaving out the others?
From the ACD Labs page about IUPAC italicization,it is stated that 


  Italicizing mainly serves to mark letters which are not involved in the primary stage of alphabetical ordering.


According to the American Chemical Society Style Guide (p. 235), the use of italics for


  positional, stereochemical, configurational, and descriptive
  structural prefixes when they appear with the chemical name or formula. 


(There are several prefixes in the list).

These are separated from the chemical name with a hyphen and are not capitalised