Mirriam-Webster defines Urtext simply as, "the original text (as of a musical score)."
On the website of publisher G. Henle Verlag, they say, "The term "Urtext" has been debated ever since it was first used. Yet the idea behind it is simple and easy to understand: the musician is offered a musical text which solely reflects the composer's intentions."
An interesting difference, at least to me. One says it is the page as it was originally published. Another says it is the sole reflection of the composer's intent.
I include in this article a link to a recent piece about Urtext music manuscripts. Where this discussion could probably provide hours of discussion for musicologists over microbrews or Manhattans, I will focus on one musician, who expressed a great deal of frustration during his early experiences with the Urtext manuscripts.
In a June 9th article in the New York Times, writer Corinna da Fonseca-Wollheim quotes Borromeo String Quartet violinist Nicholas Kitchen as saying, '“In our printed music, we have about nine dynamics, while in the manuscript there about 20 different ones,” he said describing tiny alterations to the single letter p — for “piano,” or soft — that Beethoven marked. Some have a cross on the stem, for instance, others a double cross. “There are 10 distinctions just in the area of piano.”"
Apparently, the even the published versions of those were not completely accurate, but unless you could go to the archives yourself and see them first hand, you would never know of the incredible subtleties a composer such as Beethoven wove through his music.
When I first saw musicians using i-Pads during performances, I thought it might simply be the "latest thing." I also wondered what the contingency plan was for a failed battery or dead screen. It now appears that, in some ways, 21st-century technology might give us a new peek behind the Classical music curtain.
You can read Corinna da Fonseca-Wollheim's article here.
Here is a video of the Alban Berg String Quartet playing the above Beethoven String Quartet No. 11 in f, Op. 95.
https://www.youtube.com/watch?v=ho9RvrFSIPY