Example of the structure of the directory for a drat repository for a repository with two versions (0.0.1 and 0.0.2) of hurricaneexposuredata. Directories and files shown in black are required while those in blue are optional. This example drat depository has source code available for the hurricaneexposuredata, as well as the binaries for Windows (the binaries for Mac OS X could also be included but are not shown in this example), through the optional ‘bin’ subdirectory. The top-level ‘index.html’ file can be used to customize the appearance of the webpage a user would see at https://username.github.io/drat. Functions from the drat package automate the insertion of compressed package files (‘.tar.gz’ for source code files, ‘.tgz’ for Mac OS X binaries, and ‘.zip’ for Windows binaries) within this directory structure. The ‘PACKAGES’ and ‘PACKAGES.gz’ files serve as index files, with metadata about packages available in the repository, and are created by drat::insertPackage via a call to the R function tools::write_PACKAGES.