YAML Filesystem Trees

We introduce YAML filesystem trees, a compact, human- and machine-readable representation of file and directory trees in YAML. This notation aims to offer intuitive editing and precise semantics, facilitating diverse applications: environment specification, package manifests, deployment scripts, reproducible research, and more. We describe the format, enumerate its core properties, and provide a reference implementation for recursive traversal; we also discuss applications such as copying, validation, extraction, and visualization.