What is the fine-grained topic of the following text: Validation artefacts are the tools that help parties and service providers to comply with the PEPPOL Transport Infrastructure Agreements (TIA) as they help to ensure the contents of the exchanged document instances in the PEPPOL network are valid both from a syntactical and a semantic point of view. Only return the topic.
Validation artefacts in PEPPOL Transport Infrastructure Agreements compliance