Loom patterns, commonly called loom drafts or drafts, usually are instructions on how to weave fabrics. Often, a loom pattern is composed of a four-part schematic diagram, with three diagrams showing the weaver how to set up the loom and weave the pattern, and the fourth part showing the finished pattern. For millennia, pattern designers and weavers have used various methods and personal codes to record this information. In modern times, they typically rely on graft paper charts because the paper's grid echoes the natural grid of most woven fabric. Generally, pattern makers use an X, O, or blackened square to indicate which shaft holds the heddle, while others choose to use numbers on their charts — there is not a universal way of making loom patterns.
A schematic chart, which designers typically use for loom patterns, is a block of graft paper that the pattern designer divides into four parts. Generally, a thin strip at the top is the threading draft. It shows the order in which the weaver threads the warp through the loom's heddles; a person then reads this from bottom to top, mirroring the order of the heddles.
The tie-up diagram usually is in the upper right-hand corner. This tiny block in a loom pattern specifies which shafts are to be lifted independently or simultaneously to create a shed where the weft threads pass through. A weaver reads it from left to right for the treadle sequence and bottom to top for the shaft. Generally, an O indicates the treadle and the shaft to which it is tied.
Located immediately below the tie-up diagram is the tall, narrow treadling draft. It designates the sequence for depressing the treadle to create the sheds necessary to achieve the desired pattern. Pattern makers often use numbers to identify the treadles.
The large left-hand section, often called the draw or drawdown, shows the weaver what the cloth will look like when woven. This section below the threading diagram normally is a maze of black and white squares. Although some weavers like to use colors in this chart area, other pattern designers use numbers to indicate colors and put a color key below the drawdown. This can be useful if the pattern maker designates specific yarns that correspond to a yarn company's color code.
Generally, the techniques of noting these details have changed over the millennia. For example, the southern mountain weavers in the United States commonly use a diagonal hash mark instead of an X and, for twill that requires two warp threads handled as one, they use two diagonal hash marks in each square. Many Scandinavian weavers typically number their loom harnesses differently than weavers in America, thus making their loom patterns difficult for Americans to understand. Universally, many weavers have their own shorthand methods of recording their loom patterns and these abbreviated systems have the disadvantage of being open to more than one interpretation.