http://hctxrvjzfpvmzh2jllqhgvvkoepxb4kfzdjm6h7egcwlumggtktiftid.onion/metrics-guidelines.html
Timestamp We're using the timestamp to place the data item into the right
archive file, among other things. Exception: microdescriptors do not contain
a timestamp, which makes them a pain to archive. Source identifier Ideally, we'd expect a cryptographic identifier of the
source, but if that is not available, any identifier will do.