Convert from mark twain to roede

Unit Definition (mark twain)
The mark twain or twain is an old word for the number two, derived from the Anglo-Saxon twegen. The American author Samuel Clemens (1835-1910), who had been a riverboat pilot on the Mississippi in his youth, took his literary name from a traditional riverboat phrase "mark twain", meaning "exactly two" fathoms of water. This was the minimum depth needed for the boats to operate safely without running aground.

Unit Definition (roede)
The roede is a traditional Dutch unit of distance, reinterpreted in 1820 as a metric unit equal to exactly 10 meters (32.8084 feet). The roede has also been used as a unit of area equal to one square (linear) roede; this is equal to 100 square meters or 1 are.