Weaves are formed by interlacing two sets of threads called warp and weft. Woven structures are classified as simple or compound based on the number of thread series. The repeat of a weave indicates the minimum number of warp and weft threads for a given pattern, comprising the warp and weft repeat sizes. Weaves can be represented by design drafts showing the interlacing pattern, peg or lifting plans indicating heald shaft order, and drafting plans depicting thread arrangement. Basic elements include the design, draft, and peg plan. Plain weave and twill weave are common structures.