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tratta

In Malta , a unit of volume used to describe lumber.

source

“12 palmi in length and 1 in thickness make a tratta, by which ship timber and beams for houses are sold.”

Robert Montgomery Martin.
History of the Colonies of the British Empire in the West Indies, South America, North America, Asia...
London: W. H. Allen & Co. and George Routledge, 1843.
Page 587.

A palmi would be about 10.29 inches (26.13 centimeters). Assuming this is a measure like the board foot, the third value is missing. One speculates the missing element is “1 palmi in width”, dropped by a typesetter who thought it repeated 1 palmi in thickness. But that is only a guess.