An Analysis of Metadata Encoding Standards

Like most XML applications, METS, the Metadata Encoding and Transmission Standard, overloads a small number of generic syntactic relationships (e.g., parent/child) to represent a variety of specific semantic relationships. Human beings correctly infer the meaning of METS markup, and these understandings inform the logic and design of applications that import, export, and transform METS-encoded resources and descriptions. However, METS's flexibility and generality invite diverse interpretations, posing challenges for processing across different METS profiles and local adaptations. Robust processing requires support in the form of a general software library for reasoning about METS documents. We describe the current state of development for such a library. This METS interpretation software is an application of the BECHAMEL markup semantics framework. BECHAMEL applications translate properties and relationships expressed in conventional markup into logical assertions that unpack the overloaded XML-based syntax. The inference problems we aim to support include identifying inline and external storage objects, mapping storage objects to resources and descriptions, and correctly classifying the role of namespaces. Another goal of explicating the interpretation of METS documents is to reserialize them in XML, directly asserting as many of the inferred facts as we can. In this way we hope to improve prospects for long term digital preservation.