I would like to propose a THATcamp session where I discuss the versatility and useability  of TEI, by comparing aspects of three TEI-projects I was involved in: the Streuvels letters and the correspondence between Gust Gils and Paul Snoek (both in the Centre for Scholarly Editing and Document Studies (CTB) of the Royal Academy of Dutch Language and Literature), as well as the DABNAP (Digital Archive of Belgian Neo-Avant-garde Periodicals) project from the University of Antwerp. With this, I hope to provide insight in the many ways in which TEI can be useful within a library context, as wel as provide some insight in TEI and markup language itself.