This may not technically be a new feature but slight variations on the same thing are very much in the bucket that that rule is meant to address.
This is a special case of a more general issue: follow-up posts  are not great for HN because they are repetitive, and curiosity withers under repetition. The test we apply is whether a post contains significant new information .
That would be amazing, but that story was Jan 10th. The next one was Jan 21st.
Also not the oldest, https://news.ycombinator.com/item?id=22000761 is a day earlier, and refers to a BBC report dated Jan 9th
That's yyyy-mm-dd. yyyy/mm/dd is ambiguous because the slash-separator is shared across all conflicting formats. Dashes are pretty much always ISO compliant formats. (Yes, it's a small difference, but it helps)
Conversely, there are often topics in the post that are not in the headline.
Is there a list of these somewhere? If not, then how do people decide what is and is not "on-topic"?
> metadiscussion on the is also off topic
I see meta-discussion (and similar) on HN all the time.
Is this documented somewhere as well?
Yeah, the Hacker News Guidelines: https://news.ycombinator.com/newsguidelines.html
> I see meta-discussion (and similar) on HN all the time.
Metadiscussion is usually OK. It's discouraged when the thing you're metadiscussing about is itself not on topic.
So it is, in a way.
Let's take a look:
>> What to Submit
>> On-Topic: Anything that good hackers would find interesting. That includes more than hacking and startups. If you had to reduce it to a sentence, the answer might be: anything that gratifies one's intellectual curiosity.
>> Off-Topic: Most stories about politics, or crime, or sports, unless they're evidence of some interesting new phenomenon. Videos of pratfalls or disasters, or cute animal pictures. If they'd cover it on TV news, it's probably off-topic.
"...unless they're evidence of some interesting new phenomenon"...I wonder, if one was to put a little effort into the enforcement of that guideline (applying it literally to every single political story that has appeared on HN in the last month), what do you think one might find?
Luckily, the job is now quite a bit easier, with this handy dandy new tool:
My suspicion is that we'd find there's actually quite a fair amount of political posts on HN, that people enjoyably discuss, despite them being technically in violation of the guidelines.
But also, that is somewhat tangential to the discussion in this sub-thread", which is "...appropriate for discussion...".
For that we can refer to the "In Comments" section.
Here, two items stand out to me:
>> Please don't use Hacker News for political or ideological battle. That destroys the curiosity this site exists for.
>> Please don't complain that a submission is inappropriate. If a story is spam or off-topic* (as in, evidence of some interesting new(!) phenomenon), flag it. Don't feed egregious comments by replying; flag them instead. If you flag, please don't also comment that you did.
Once again, if one was to put a little effort into investigating the historic enforcement of that guideline, what do you think one might find? Note that I pose this more as a sincere question intended to enhance thoughtful discussion, as opposed to a confident assertion of fact, or accusation. It seems like a perfectly worthwhile topic of discussion - after all, while we here at HN may have higher-than-average intelligence, and knowledge of world affairs and how things generally work...are we not also human, and therefore subject to the same shortcomings of all people, if to a lesser degree?
In my experience, the evaluation of what is or is not "political or ideological battle" may suffer, at least to some degree, from the shortcomings I refer to above. Of course, I may be 100% incorrect in that judgement. But it also seems possible that I'm not 100% incorrect. Which is it? Who among us know the truth of such matters? Does anyone care? If all of us are "super chill" and comfortable with free speech (as opposed to enforcing certain boundaries), then there should be not problem whatsoever.
>> Please don't post insinuations about astroturfing, shilling, brigading, foreign agents and the like. It degrades discussion and is usually mistaken. If you're worried about abuse, email us and we'll look at the data.
Of course such things are a matter of opinion, but I think a decent case would be made that this happens from time to time.
> Metadiscussion is usually OK. It's discouraged when the thing you're metadiscussing about is itself not on topic.
It is certainly discouraged culturally, but is is contrary to the explicit guidelines? Or, might it be possible that there's somewhat of an unmentioned Overton Window in play here at HN, that is subtly (but not explicitly!) enforced? 
>> Be kind. Don't be snarky. Have curious conversation; don't cross-examine. Comments should get more thoughtful and substantive, not less, as a topic gets more divisive.
I'm obviously a bit biased (but then who isn't), but curiosity is not the feeling I get when certain topics are being discussed. YMMV.
>> The Overton window is the range of policies politically acceptable to the mainstream population at a given time. It is also known as the window of discourse. The term is named after Joseph P. Overton, who stated that an idea's political viability depends mainly on whether it falls within this range, rather than on politicians' individual preferences. According to Overton, the window frames the range of policies that a politician can recommend without appearing too extreme to gain or keep public office given the climate of public opinion at that time.
Again, I pose these questions and ideas as sincere questions intended to enhance thoughtful discussion, as opposed to accusations or confident assertion of fact. To me, this is what productive conversations on complicated topics should consist of, if we want to make any actual progress on some of these problems.
Perhaps everything I say here is incorrect, invalid, or maybe even ignorant. If that is indeed true (which first requires an evaluation), I would think that fact should be demonstrable (via rational, evidence-based discourse) - but in my experience, such judgements are typically declared by fiat, as if they are somehow self-evident, no discussion needed.
I'm more interested in having some conversations that consist of something a little more deep than the standard tribal warfare. Do you have any thoughts (agreement, disagreement, criticism) on what I've written?
Anyways this is great, thinking if I could integrate some features into the app.
Considering this was posted just 2 days ago by yourself and there’s a pretty active discussion there, this thread is unnecessary.
Personally, this is one of the most useful and thought provoking demonstrations of leveraging pre-existing information that I have ever encountered.