exists physically in digital technology as a string of bits,
Yes, an excellent point. In a way there are multiple realities going on for digital documents. They exist as code (and many different layers of code if I understand the OSI model correctly) which many people would fail to interpret in a meaningful way when presented with it directly (I certainly would). Though I suppose the code itself expressed visually or in some other way could have some inherent interest. They also exist as they "are intended" by whomever created them opened by the software they were created for and, in addition, they might possibly exist opened through alternative software which could produce different (if perhaps, indecipherable) results.