First page Back Continue Last page Overview

At first sight, a header looks simple: relating some variable values to labels (each set is named a field), which could simply be stored in a hash.

However: fields can appear more than once in the same header, so to do things right you cannot use a normal hash. Besides, the order of the fields should be preserved, although that is only important for certain fields, not all of them. So headers are not simple after all!