Charles Olson, one of America's most profound modern poets, created the idea of "projective verse" which, according to him centers around the idea of the poem's lines being reflective of the actual meaning of the poem using breaks to synchronize with the breath of the reader. This is particularly relative to situation in that the work then works with the situation; that is to say it is in sync with the situational being of the poem itself.
Most of Olson's book, "The Maximus Poems," centers around the idea of a modern, American based epic. It largely is influenced by the idea of French Lettrism, an avant garde movement of the early-mid 1900's. Lettrism, specifically in terms of poetry, centers around the idea of the Lettrie, the idea that the poem should be purely formal. It should essentially be, itself, a situation.
A great deal of Olson's work in the book has to do with America's situation in history: the idea that we don't have the background that so many great empires in Italy and Greece had. Thus he writes an epic poem based on a country that is somewhat less than epic.
Repetition, or the lack-thereof, remains important in the idea that the poem mirrors the situation of America. This mirrors America's very brief and original history.
Olson truly had a great deal of groundbreaking executions in the poetry of modern America; his allegiance to the avant garde writing style of French Lettrism and his faithfulness to the attempt at a modern epic were truly great examples of the situation brought into the literary field. His work is recognized as some of the most influential that the past 100 years of writers had to offer.