Raine wrote the following in an email under the heading linking and addressing in response to a comment I made about putting in anchor tags for each paragraph:
1 Why stop at paragraphs? Then we’ll just be having this same conversation five years from now about needing word-addressable links.
2 It doesn’t address the core issue of impermanence that will underline any addressing scheme (dead links).
To flesh this out more, we can approach addressability in two contrasting ways:
1 Immutability – Creating an immutable (permanent) snapshot that can be referenced with a high degree of granularity and reliability. With per-character fidelity, linking can reliably be based on the arbitrary (non-semantically motivated) value of character index (start and end).
2 Tolerance – Combining redundancy, flexible parsing, and heuristics to increase the resiliency of links to inherently impermanent/degradable sources. For example, one could reference “Paragraph 3” or “The paragraph starting with ‘I’m a big fan of transclusion.'” Similar to HTML’s philosophy.
I don’t think we need to stop at paragraphs, the anchor tags are just there to help with the addressing. The tolerance you mention is key, both for finding text in the document (second sentence after a particularly anchor tag fx.) and for finding the document, which should be possible by location/server, name or other criteria.