Many traceability models lack well-defined traceability link types, provide incomplete coverage of situations, do not provide mechanisms to ensure consistency of traceability, and consider only requirements traceability ignoring other activities of development. We propose a set of basic concepts for traceability, a reference model, and a comprehensive metamodel for traceability created using this reference model. The reference model defines: basic elements for traceability, basic actions to be done on artifacts, basic properties that sets of link types and artifact types should have, basic categories that should be realized regarding these sets, and basic set of processes for traceability. The metamodel is composed of a visual model defining how its elements interact, the definition and semantic description of link types and artifact types which realize the categories of the reference model, and a set of detailed processes describing the steps to maintain traceability and system consistency. Our proposal aims to reduce the problems identified; the reference model provides directions to help the creation, or evaluation, of a traceability model; the metamodel provides semantically described traceability link types, coverage of the most common situations, mechanisms to ensure consistency of traceability, and covers the most common activities in software development.