The usage of structure definitions is quite commonplace
among forth implementors. The actual implementation
techniques vary as widely as the resulting capabilities
of the resulting structure-"types".

During the years, a common minimum characteristics can
be deduced from the implementations that manifest
themselves in the three words

> STRUCTURE ( "structure name" -- xx end_offset )
> END STRUCTURE ( xx end_offset -- )
> SIZE OF ( "structure name" -- size of_it )