Ad-hoc data exchange, e.g., by sending email attachments, leads to multiple copies or versions of a document at dispersed nodes in a network. However, their relationships such as is-a-version-of are lost. The relationships between a single document's existing versions together with the versions themselves form a so-called document flow, which allows to trace where a document originated and how it was distributed from node to node. The paper proposes an ontological, machine-processable framework for semantically describing and thus revealing document flows. The presented approach provides a light-weight communication infrastructure for information exchange and collaboration that is based on distributed versioning of documents and offers flexible document annotation mechanisms. After describing our infrastructure model, we present the implemented prototype and discuss a range of application scenarios for traceable document flows (TDFs).