cuerda ("Spanish acre") to acre conversion

cuerda ("Spanish acre") to acre conversion   (08/16/2013, 5:04 PM)

I would like to know where I can get the OFFICIAL definition of the amount of acres in 1 cuerda (its sometimes called the "Spanish acre", probably because it may have originated in 17th/18th century Spain). Cuerda is the universal unit of land measurement in Puerto Rico. It is the only unit used by the Government of Puerto Rico, the Courts, etc. Its also used by realtors, homeowners, land engineers, land surveyors, etc. I already know that 1 cuerda ≈ 0.97. The problem is that some sources say it equals 0.97122191 acres while others say it equals 0.97112414. I need to know who is correct and WHERE they are getting their OFFICIAL cuerda definition from. Any help will be appreciated. Thanks. CR