What is a better way to mark answers as obsolete? [duplicate]

Question

Answers sometimes become obsolete. New solutions arise that were not technically feasible at the time that the question was originally posed. People decide that the old way of doing things is no longer a good idea. This goes for answers on main sites as well as on meta sites.

In How to deal with obsolete answers?, several suggestions were raised, but I don't find them satisfactory.

• Deleting is not appropriate, I think, since it removes all trace of the answer, and even obsolete information is sometimes useful. It leaves a void, and there is even a risk that the void could be filled by someone else writing a similarly obsolete answer. I also believe that is is inappropriate to strip the original poster of reputation points that were rightfully earned in the past.
• Editing the answer to provide a new solution is an underhanded approach, since the practice of radically altering posts is prone to abuse. Who is to say that all the voters who upvoted the original answer agree with whatever new advice is added? It's even worse if someone other than the original author of the answer violates the author's intent. Editing also fails to confer reputation commensurate with the effort, if the new answer is completely different. Additionally, it might not be desirable to bump an old post onto the front page.
• Downvoting To counteract all of the upvotes, you would have to rally a downvote brigade, which is neither realistic nor desirable. There's no need to hurt the original poster's reputation just because an answer is no longer relevant. Furthermore, all previous upvotes are locked in unless the post is edited, so the concerns raised above about editing also apply.
• Commenting is insufficient, because it could be buried at the bottom of a long thread. Also, comments on Stack Exchange are designed to be of a somewhat transient nature. Comments also don't alter the order of presentation of answers.
• Locking is currently possible only for a "Content dispute" or for "Offtopic [sic] comments". As the guidelines say, "posts should only be locked when something seriously bad is happening. A locked post cannot be changed in any way or voted on". I don't think that obsolete information qualifies as "seriously bad", or that editing/voting should be prevented.

I think a feature enhancement is called for!

Answer 1

A moderator post notice could fit the bill nicely. Currently, there are three types of notices:

1. citation needed

   This post does not cite any references or sources. Please help improve this post by adding citations to reliable sources. Unsourced material may be challenged and removed.

2. current event

   Post is related to a rapidly changing event.

3. insufficient explanation

   We're looking for long answers that provide some explanation and context. Don't just give a one-line answer; explain why your answer is right, ideally with citations. Answers that don't include explanations may be removed.

I propose a fourth type:

4. obsolete

   This post may contain obsolete information.

It would be nice if answers were ordered such that posts marked as obsolete were sorted as if they had a score of 0.

Some advantages of this approach include:

• The notice would be more prominent than a comment.
• Readers can draw their own conclusions as to what to do with the information.
• Previously earned reputation is preserved.
• Other answers can bubble up to the top.
• This feature piggybacks on an existing feature (in fact, it complements the "current event" post notice).

The only drawback I can think of is that it places moderators in a position of having to judge whether to post the notice, but I don't think that it is significantly more burdensome than with the existing kinds of post notices.

Answer 2

I think adding a new flag will be a good solution.

It will work like this:

1. User finds a question or answer which is out-dated
2. (S)He will flag the question or answer as outdated
3. Moderator or high-reputation user will be able to see such flags
4. Verification
5. If obsolete then the question or answer is marked as obsolete

This must be coupled with the ability to search only for posts marked as obsolete which can then be updated with appropriate information.

1. This will help the community to view specifically just questions/answers with obsolete mark and will enable quick update of information.

2. People who are searching for answers to such questions will proceed with caution when using/applying answers flagged out of date

3. This will definitely improve the quality of community wiki posts and facilitate preferential update of such posts which should be maintained up-to-date

This will work better if a higher amount of reputation is given when users update an obsolete post and it is accepted.

Answer 3

so-called "Out of date" answers aren't always bad answers.

Sometime people need information that you would consider to be "Out of date" This is especially true if the reason why the answer is "out of date" is because the technology changes.

Going by the technology changing example:

When new technologies come out, the old ones don't just evaporate and disappear. Normally, there are people who still use them, and they still need answers which apply to the old technologies.

You might be tempted to tell them to just update their technology, but it can cost a lot of money and/or time to update technologies, and sometime it actually makes financial sense to just not upgrade.