In libraries, marginal space is a rather technical term used primarily to refer to binding -- what we do to assemble pages into a unit, or volume. The pages must have blank space at the edges that will be joined, or else the binding will prevent the reader from seeing what was there. A book or journal can have wide margins (good for blinding) or tight margins (not so good).
Marginal space is a concept that is also used in many, many other domains. Here are just a few examples.
"Liminality is not concerned with the old strategies of the edge, the avant garde and the marginal. Instead it is a notion offering a new way to experiment and create using the in between spaces, the interstices. Liminality is fluid, open, unfixed, inclusive, diverse." Shards of Memories, Fragments of Sorrows: Transforming Marginal Space into Liminal Space for Women in Theatre (PDF: large)
"Today the Marginal space grows wider and more interesting while the space for the main text seems to shrink in significance."
Judith McGrath, Carolina Arts, November 2004.
"Marginal space is public space that, lacking satisfactory levels of design, amenities, or aesthetic appeal deters members of the public from using the space for any purpose."
NYC Dept. of City Planning
"If you're working with marginal space ... Well, one of those spaces is on the edge of the law." Adam Chodzko
"Society can establish a stable position by creating some marginal space. Often, only by creating an outside, by creating ideological dichotomies a society can generate stability."
So, me? I am fascinated with margins, spaces, boundaries, how and why we decide what and who fits in which boxes, and then also how to blur or make crisp the edges between boxes and boundaries and edges. This is my space to explore marginal space.