1) The full protein sequence. This sequence is included as a key, allowing segment labels in the bracket itself to be abbreviated. All amino acids are shown as they are in the final protein and differences are marked on segments. Segments are typically abbreviated to only the first and last aa, as these residues are most relevant for evaluating strategies. 2) Ligation reactions. Segments are joined two at a time, giving the bracket its characteristic shape as ligation intermediates gradually combine to form the final protein. Each reaction shows the initial starting segments, the product isolated after all one-pot transformations, and a brief description of reaction conditions. Sequential reactions are stacked so one may trace the full pathway from any single segment to the final product. 3) Side-chain modifications. Deprotection, desulfurization, and other side-chain modifications are essential to many strategies, and any differences from the final protein should be clearly labeled on relevant segments. If a reaction is performed on a purified ligation intermediate, the segment should be shown both before and after modification; if performed one-pot with ligation, only the final product must be shown. 4) C-terminal modifications. Unless otherwise specified, segments are assumed to contain an amine at their N-terminus and carboxylic acid at their C-terminus. In most CPS strategies, however, all segments except the last contain a reactive group at their C-terminus (e.g., a thioester or hydrazide for NCL) that should be clearly indicated. The level of detail for this label varies, but simple text is usually sufficient when standard techniques are used. Assembling this information by drawing shapes and manually editing text labels is tedious. Due to the repetitive nature of the figure, however, we reasoned that most of the pieces of the bracket, including all intermediates and the final protein, could be extrapolated if we knew only the starting segments and order of reaction steps. Using this principle, we developed a simple plain-text code that uniquely identifies each CPS strategy, called "bracket notation" (Figure ), and an algorithm to translate this code into a figure.