A draft is written from a tray: the brief, which holds the instructions, and documents excerpted from a record. In one case a phrase that was in none of the record came back in the draft anyway. It stood in the title of one tray document.
The title of one tray document, its file name and the brief’s file list
The phrase is “What disproved it”. The word “disproved” is not in the record the draft was written from. It is in that tray document’s title, in its file name and in the brief’s file list.
The draft carried the phrase in a sentence of its own: “What disproved it was the update list.” That sentence combined the tray document’s title with the brief’s gloss. A gloss is the brief’s own wording for something in a document.
The test
The change was only the four tray # title lines and file names, to unit-only wording (“Three sentences” for “What disproved it”).
There were three fresh runs. With the content titles the phrase was present (1 of 1). With unit-only titles it was absent (0 of 2).
That is consistent with the tray title and file name carrying the phrase. The measurement is those three runs.
A carrier the test left alone
The brief’s glosses are another carrier that the test did not touch, and one came back in every run.