 Names of unbranched alkanes and alkanols, like "normal butane" and "normal propyl alcohol", which are obsolete now, 
have become the prefix "n-", however, not "nor".Other "normal" compounds got the prefix "nor".Older trivial names, like norleucine and norvaline should be abandoned; the use of the prefix for isomeric compounds was already discouraged in 1955 or earlier.