Living inside built environments - infrastructure - it is easy to take for granted the things that we do not need to engage, but are at work behind the scenes nonetheless. Well-designed systems become invisible, but to engage them, how do we know which perspectives, objects, and relationships are useful? I examine the University of Michigan Digital Library (UMDL), a mid-1990s interdisciplinary project attempting to build an agent-based digital library architecture. Through analyzing project data, I develop the concept of ontic occlusion and exposure - mechanisms of choice regarding objects and relationships that enter discourses and representations.

By analyzing project artifacts, interview transcripts, and meeting records, this study identifies key sets of discursive elements bridging concepts between disciplinary communities on the surface, but were the fundamental sites of contestation between groups' understanding of project goals. I examine narratives of project personnel to understand the positioning of terms and ideas relating to project design, execution, and assessment, and discuss the role of the ontic in interdisciplinary work.

Using data from the UMDL project, I discuss the tension between occlusion (the hidden) and exposure (the revealed) in understanding the digital library as an object through meetings of the project operating committee - the primary engagement site between researchers from different departments, primarily computer engineering and library science. Examining interpretive differences, use of fundamental terms, and observations about the contested responses toward resolution, we can better understand the outcomes of the project, the disciplinary positioning of institutional change, and perspectives of evaluating the project in the subsequent years.

This dissertation contributes to an understanding of discourse development in interdisciplinary projects where shared language is important to design, execution, and evaluation. It combines perspectives in philosophy, digital libraries, and interdisciplinarity studies. The complementary mechanisms of ontic occlusion and exposure are useful devices to decode and describe change in sociotechnical systems, and highlight the need to examine more closely both what is rendered in accounts of infrastructure, and residual categories often left unaddressed.