Urtext
Definition: the original text of something; esp. music
“ur-” is German for “original” or “primitive.”
The urtext is the original document, without any changes. It’s often used to discuss printed music, as these tend to change over time to accommodate new notation or musical styles.
Why I Looked It Up
From The Real Work, discussing the mythical S.W. Erdnase, a pen name adopted by the author of a seminal book on card tricks.
Erdnase is everywhere. […] He is the subtext, and sometimes the ur-text, of so much else.
Note that I didn’t find the hyphenation anywhere else when researching this.
Update
Added on
In Spam: A Shadow History of the Internet, in a discussion of Nigerian 419 email scams:
[the details in the emails are] as evocative of remote and unknown sites of money and power as some invented Damascene castle of Galician dungeon must have been in the first centuries of the Spanish Prisoner con, which is the urtext of what is played out in this emails.