You can also have the case where the human reading the document thinks something in there is instructions and they are not.
There's a well known anecdote supposedly from the famous mathematician John Littlewood where he wrote a paper about some optimization problem and the last sentence was something like "Make X as small as possible".
The typesetter thought that was instructions to him, and so omitted that sentence from the paper and made every X as small as he could.
There's a similar story about J. Edgar Hoover scribbling "watch the borders" on a memo, which was intended to be a formatting comment, but was interpreted as instructions.
There's a well known anecdote supposedly from the famous mathematician John Littlewood where he wrote a paper about some optimization problem and the last sentence was something like "Make X as small as possible".
The typesetter thought that was instructions to him, and so omitted that sentence from the paper and made every X as small as he could.