What does "Directory guard" design means in the following context and could somebody elaborate on this Tor FAQ quote?

Question

Following, please find a quote from Tor FAQ :

"Restricting your entry nodes may also help against attackers who want to run a few Tor nodes and easily enumerate all of the Tor user IP addresses. (Even though they can't learn what destinations the users are talking to, they still might be able to do bad things with just a list of users.) However, that feature won't really become useful until we move to a "directory guard" design as well."

1. What does "directory guard" design means in the above quote?

2. What does the last sentence in the above quote is implying?

Answer 1

A directory guard is a relay that your Tor client picked to download directory information from. Directory information is metadata about the Tor network - the list of relays (consensus), and descriptors for all the relays. This can be different from the relay you're using to make anonymized connections. The sentence is implying that this scheme I've described above hasn't been deployed.