BNP Specification

BCML's preferred mod format is an open specification developed organically alongside BCML: BOTW Nano Patch, or BNP. It is designed to be smaller, more precise, more broadly compatible, and less subject to copyright claims than previous formats for BOTW mods.

A BNP mod consists of three parts—general game files, merger logs, and metadata—packaged in a 7-zip archive with the extension .bnp. Original content and any modified content not handled entirely by an automated merger are placed in content and aoc folders in exactly the same way as a BOTW graphic pack. Merger logs are contained in the logs folder, and they are plain text files recording any modded content which can be handled by an automated merger. At present logs are recorded as YAML or CSV, but the update to the BNP format with BCML 3 will change this to JSON. Finally, metadata is stored in a Cemu-style rules.txt, but with some additional permitted fields (image, url).