I'm sorry I can't bring more clarity to the term "half-canvas." The problem is, half-canvas means different techniques to different makers. Some do it one way, some another. Generally, you can read half-canvas to imply that some part of the front of a coat that might have been sewn has been fused instead, usually to save labor expense. Two common techniques already have been mentioned in this thread: One is fusing the coat front from the shoulder toward the lapel, then changing the construction to sewn canvas near the lapel to achieve a soft and resilient roll; the other technique is to divide the coat horizontally, using canvas for the upper part and fusing for the lower. Two points to remember: Fusing doesn't necessarily imply inferior quality. In his book, Joseph Abboud recalls his days as a buyer at Louis Boston. He says that he wrote big numbers with a German company that made a fully fused gabardine suit, a much cleaner suit, he argues, than the same cloth hand sewn. Second, fusing is not as simple as gluing the skin of a suit to the same canvas that could have been hand sewn. In other words, fusing does not replace sewing one-to-one. Fusing replaces the canvas with a heat- and pressure-sensitive armature of synthetic materials that can be pressed to the desired contour. I have a good, though lengthy, article from Bobbin magazine explaining the three principle tailoring techniques. I'll try to retrieve it.