unitizerSectionExpression-class contains the actual expressions that
belong to the section, whereas unitizerSection-class only contains
the meta data. The latter objects are used within ]unitizer-class,
whereas the former is really just a temporary object until we can generate
the latter.
title1 lenght character, the name of the section
detailscharacter vector containing additional info on the section
comparefunctions to compare the various aspects of a
unitizerItem-class @slot length tracks size of the section
unitizerSectionNA-class is a specialized section for tests that actually
don't have a section (removed tests that are nonetheless chosen to be kept
by user in interactive environment)