The other added a fourth story and classic New Orleans balcony rails. Today, though they no longer have their original roofs, both owners have constructed new roof cornices that are identical not only to each other, but to their original form. As the palimpsest suggests, writing has been especially capable of retaining this sediment of past ideas. Other forms of revision are not as kind to the history of a document. The censor's mark actually obscures the text it refers to, as in an FBI file made public only after key events and names have been obscured by black bars.
Facsimiles can eliminate data as needed.
But the digital processes for creating and editing text, images, movies, etc., have led to a world where the remnants of missteps and mistakes are overwritten, wiped away. The antithesis of the palimpsest with its visible history, documents on the computer are reduced to a constantly updated present tense. Erasures on an architectural sketch are just-visible evidence of similar processes and potential results. Photoshop 2.5, released in 1993, was one of the more sophisticated image processing programs of the time. To be sure, one could save each revision of an image separately, but that is a different thing altogether.