In German linguistics, the Speyer line, or Main line (Main river) is an isogloss separating the dialects to the north, which have a geminated (lengthened) stop in words like Appel "apple", from the dialects to the south, which have an affricate: Apfel. The line runs from east to west and passes through the town of Speyer. In Germany, the line is best known by its humorous designation Weißwurstäquator, the white sausage equator.