A "pole" is a unit of length that is equivalent to 16.5 feet or 5.0292 meters. It is sometimes referred to as a "rod" or a "perch," and these terms are often used interchangeably. Poles, like rods and perches, were historically used in some English-speaking countries, primarily in the United Kingdom and the United States, for land measurement, surveying, and real estate.
While the use of poles, rods, and perches has become less common in modern times, you may still encounter these units of length in certain contexts, especially in older land descriptions or surveys. In everyday measurements and official standards, more commonly used units like meters or feet are preferred.
The term "long reed" does not refer to a standard unit of measurement or a widely recognized term in contemporary systems of measurement. It's possible that "long reed" is used in a specific context or industry, but it does not have a standard definition in general measurements.
If you have more context or specific information about how "long reed" is used, I would be happy to try to provide a more precise explanation.