What is "terrantez"

Terrantez (also known as Cascal) is a white Portuguese wine grape variety that was once widely used on the island of Madeira to make the sweet fortified wine for which the island is known. Today, the variety is nearly extinct on the island. There are still some limited plantings in the Minho Province where, as Cascal, is a permitted blending variety with Alvarinho and other grapes in the Denominação de Origem Controlada (DOC) wine Vinho Verde. As Terrantez the grape is permitted in several of the Indicação de Proveniencia Regulamentada (IPR) regions of the Azores including Biscoitos IPR on Terceira Island, Graciosa IPR on the white island of Graciosa and Pico IPR on Pico Island.