user1530: As part of solidifying & simplifying our rules, let's look at tagging next.
The fact that our tagging is confusing  has been brought up a few times in the past, and our current approach to creating new tags is somewhat case-by-case. For anyone unfamiliar with the site it's a little confusing why some tags get split and some don't. There have been multiple meta posts asking about it in different forms - so let's pin it down and decide solidly.
In this policy review, let's look at how we tag series that have multiple continuities. That is, series that have significantly different plots/stories and are essentially sub-series.
Some examples of this would be Fullmetal Alchemist and Fullmetal Alchemist: Brotherhood, The Evangelion TV Series / Evangelion Movies, and so on.
There are a couple of approaches we can take here and we'd like to hear what the A&M community wants to do.

user63: I feel that we need a change. Our current policy on this makes things a bit vague and just seems lazy overall. I feel that the mods share some of the blame in their lack of action on the matter. 
Because this has been brought up multiple times, it's about time we make an attempt to take action on the matter. Just putting it off til later merely delay the inevitable.
Why should I care?
First off, I personally think it makes for bad policy to have the tags be inconsistent. It feels a bit lazy to lump the whole of one series with different continuities under just the umbrella of one tag. Having multiple tags to differentiate a series will make it easier for both asker and answers as these questions will better establish the context of which series on is referring to. This will better confine the scope of the question to only that series, making most question easier to answer as you don't have to cover all the continuities if the OP doesn't specify. 
Remakes and reboots fall under the same umbrella. Series like Hunter x Hunter and Ghost in the Shell often times change up the plot, alter scenes, and/or even add additional characters. Being able to make a distinction between the original from the remake can make answering one much easier, especially when you haven't seen one of them. This allows fans who are "experts" fans on one series to be able to seek out and cover the one that they are most familiar with.
What does this mean?
This doesn't mean every tag needs to be separated or be differentiated with an -anime, -manga, or -live-action suffix. It means we need to make a distinction between them. For example, by splitting fullmetal-alchemist into "fullmetal-alchemist-2003" and "fma-brotherhood" we can better focus on easy particular continuity and not have to specify which one we're talking about each time. It's the same logic as not needing to include the title series title in the question title when posting a question to reduce redundancy. 
If a user asks about an event in a series with two different continuities (with a different outcome) and doesn't make a distinction as to which they are referring to, covering both might be require additional effort, especially if you've only seen one of them. It's a bit cumbersome to ask a Gundam Build Fighters specific question and need to differentiate it from the original Gundam or the Gunpla Builders Beginning G OVA, when all you have is the gundam tag. A tag should refer specifically to a particular series rather than the franchise as a whole.
What we need is a clear set of guidelines to abide by. The an older series shouldn't be given precedence over a new one. If the titles are the same, we should add a date to both. If the difference between a manga and an anime is somewhat minor (no major divergences in the plot [e.g., the Angelic Layer anime vs manga and the Akame ga Kill anime vs manga, compared to the Shomin Sample anime vs manga]), there should be no need to separate the two (i.e., they'll fall under one tag). 
Should there be exceptions?
There may be special circumstances to warrant separation. For an example, Dragonball, Dragonball Z, Dragonball GT, and Dragonball Super can be different enough to warrant separate tags while being all a part of one continuous series with shared characters, compared to Naruto and Naruto Shippuden, which should not. The Fate/Stay Night falls in a similar category, we should refer to the Deen TV anime as separate from the Deen UBW, which is separate from the ufotable remake of UBW and Heaven's Feel. Evangelion should be separated into the TV series, End of Evangelion movie, and the Rebuild movies. This way we can make a distinction and better focus on the topic specifically, rather than generalize them. 
What should we do?
I propose that if we would like split series with different continuities establish an meta where we clarify everything from the guidelines of how to approach tagging to any exceptions to these guidelines, along with an explanation of why decide to do things this way. This would eliminate any confusion on the topic and set a precedence for future series as well.
Less isn't always practical, but consistency and clarity are. While it may require more work (for the mods and community; retagging question, synonymizing,  making better tag excerpts and wikis, etc.) as a whole, I feel that starting to be more consistent with our current site policies can better shape our attitude and outlook on future policies as well.

user1530: I think the best approach is to Keep It Simple. We should use a single tag for these related series.
I realise the benefits of being able to look up FMA:B rather than FMA, but it gets very complicated quickly - when is something a continuity? do we tag all the Dragonball series and all their movies? 
It also opens the floodgates for considering even more tags, consider attack-on-titan-manga , attack-on-titan-anime , attack-on-titan-junior-high and even attack-on-titan-live-action. There may be questions about the series as a whole too. "Why are the titans attacking?" for example.

There aren't many questions for most series, the only ones that will benefit are the largest (FMA, is admittedly an example). Otherwise, we have 2 tags for maybe 3 questions (if even). 
This also means an increase in the amount of retagging we need to do, the amount of tags we fall behind on season-by-season, etc.

I think having less tags, while less convenient for searchers is the more practical approach.

user7579: I've appreciated SciFi and Fantasy SE's approach more and more as time goes on. For large franchises like Star Trek and Star Wars, SFF has a single tag for the franchise, and then tags for the specific properties in the franchise. For example, they have a star-trek tag, and then star-trek-tos, star-trek-tng, and so on. Questions about the franchise in general will be tagged with just the franchise tag. Questions about a specific series will have the franchise tag as well as the tag for the specific series.
So in our case, we would have an evangelion tag and then eva-tv, end-of-eva, rebuild-of-eva. Questions about the franchise as a whole, or which are open to answers drawn from any part of the franchise, can be tagged evangelion. Questions which are additionally focused on a single property would also have a specific tag. E.g. "Why was Asuka designed with red hair?" would be tagged evangelion because Asuka's character design pertains to the entire franchise and not just a specific series. "Why did Asuka say 'Kimochi warui'?" would be tagged evangelion end-of-eva; this way it shows up in searches for evangelion questions, but it's also obvious that the question pertains to end-of-eva. This also solves the problem of specific tags that only have two or three questions; while there will be such tags (I don't know that we'll have many questions on eva-angelic-days, for instance), the questions will be double-tagged as evangelion, so all the Eva questions can be aggregated when necessary.
While I think this would solve our problem, it has two disadvantages. First, it's high maintenance. We would probably need high rep users to buzz around adding and subtracting tags to make sure that every question conforms to the convention. 
Second, we'll have to make up our own names for cases like the 2003 Full Metal Alchemist anime, because the tag would need to be distinct from the main full-metal-alchemist tag as well as the fma-manga tag. I don't particularly like ʞɹɐzǝɹ's solution of adding dates and studios (fma-2003 or unlimited-blade-works-deen) as these shows are not commonly known by those titles, which means people will be even more likely to tag incorrectly and make more work for other users. I don't have a better idea, though. 

1530: <p>As part of <a href="https://anime.meta.stackexchange.com/a/2672/1530">solidifying &amp; simplifying our rules</a>, let's look at tagging next.</p>

<p>The fact that our tagging is confusing  has been brought up a few times in the past, and our current approach to creating new tags is somewhat case-by-case. For anyone unfamiliar with the site it's a little confusing why some tags get split and some don't. There have been <a href="https://anime.meta.stackexchange.com/questions/2673/why-fma-and-fma-brotherhood-didnt-have-different-tag?s=1%7C1.2682">multiple</a> <a href="https://anime.meta.stackexchange.com/questions/308/should-multiple-continuities-have-individual-tags?s=5%7C0.0835">meta posts</a> <a href="https://anime.meta.stackexchange.com/questions/84/should-minimalistic-tags-and-synonyms-be-used-for-anime-with-different-series/88#88">asking</a> about it in different forms - so let's pin it down and decide solidly.</p>

<p>In this policy review, <strong>let's look at how we tag series that have multiple continuities.</strong> That is, series that have significantly different plots/stories and are essentially sub-series.</p>

<p>Some examples of this would be Fullmetal Alchemist and Fullmetal Alchemist: Brotherhood, The Evangelion TV Series / Evangelion Movies, and so on.</p>

<p>There are a couple of approaches we can take here and we'd like to hear what the A&amp;M community wants to do.</p>
 63: <p>I feel that we need a change. Our current policy on this makes things a bit vague and just seems lazy overall. I feel that the mods share some of the blame in their lack of action on the matter. </p>

<p>Because this has been brought up multiple times, it's about time we make an attempt to take action on the matter. Just putting it off til later merely delay the inevitable.</p>

<h2>Why should I care?</h2>

<p>First off, I personally think it makes for bad policy to have the tags be inconsistent. It feels a bit lazy to lump the whole of one series with different continuities under just the umbrella of one tag. Having multiple tags to differentiate a series will make it easier for both asker and answers as these questions will better establish the context of which series on is referring to. This will better confine the scope of the question to only that series, making most question easier to answer as you don't have to cover all the continuities if the OP doesn't specify. </p>

<p>Remakes and reboots fall under the same umbrella. Series like <em>Hunter x Hunter</em> and <em>Ghost in the Shell</em> often times change up the plot, alter scenes, and/or even add additional characters. Being able to make a distinction between the original from the remake can make answering one much easier, especially when you haven't seen one of them. This allows fans who are "experts" fans on one series to be able to seek out and cover the one that they are most familiar with.</p>

<h2>What does this mean?</h2>

<p>This doesn't mean every tag needs to be separated or be differentiated with an -anime, -manga, or -live-action suffix. It means we need to make a distinction between them. For example, by splitting <a href="https://anime.stackexchange.com/questions/tagged/fullmetal-alchemist" class="post-tag" title="show questions tagged &#39;fullmetal-alchemist&#39;" rel="tag">fullmetal-alchemist</a> into "fullmetal-alchemist-2003" and "fma-brotherhood" we can better focus on easy particular continuity and not have to specify which one we're talking about each time. It's the same logic as not needing to include the title series title in the question title when posting a question to reduce redundancy. </p>

<p>If a user asks about an event in a series with two different continuities (with a different outcome) and doesn't make a distinction as to which they are referring to, covering both might be require additional effort, especially if you've only seen one of them. It's a bit cumbersome to ask a <em>Gundam Build Fighters</em> specific question and need to differentiate it from the original <em>Gundam</em> or the <em>Gunpla Builders Beginning G</em> OVA, when all you have is the <a href="https://anime.stackexchange.com/questions/tagged/gundam" class="post-tag" title="show questions tagged &#39;gundam&#39;" rel="tag">gundam</a> tag. A tag should refer specifically to a particular series rather than the franchise as a whole.</p>

<p>What we need is a clear set of guidelines to abide by. The an older series shouldn't be given precedence over a new one. If the titles are the same, we should add a date to both. If the difference between a manga and an anime is somewhat minor (no major divergences in the plot [e.g., the <em>Angelic Layer</em> anime vs manga and the <em>Akame ga Kill</em> anime vs manga, compared to the <em>Shomin Sample</em> anime vs manga]), there should be no need to separate the two (i.e., they'll fall under one tag). </p>

<h2>Should there be exceptions?</h2>

<p>There may be special circumstances to warrant separation. For an example, <em>Dragonball</em>, <em>Dragonball Z</em>, <em>Dragonball GT</em>, and <em>Dragonball Super</em> can be different enough to warrant separate tags while being all a part of one continuous series with shared characters, compared to Naruto and Naruto Shippuden, which should not. The <em>Fate/Stay Night</em> falls in a similar category, we should refer to the Deen TV anime as separate from the Deen UBW, which is separate from the ufotable remake of UBW and Heaven's Feel. Evangelion should be separated into the TV series, End of Evangelion movie, and the Rebuild movies. This way we can make a distinction and better focus on the topic specifically, rather than generalize them. </p>

<h2>What should we do?</h2>

<p>I propose that if we would like split series with different continuities establish an meta where we clarify everything from the guidelines of how to approach tagging to any exceptions to these guidelines, along with an explanation of why decide to do things this way. This would eliminate any confusion on the topic and set a precedence for future series as well.</p>

<p>Less isn't always practical, but consistency and clarity are. While it may require more work (for the mods and community; retagging question, synonymizing,  making better tag excerpts and wikis, etc.) as a whole, I feel that starting to be more consistent with our current site policies can better shape our attitude and outlook on future policies as well.</p>
 1530: <p>I think the best approach is to <a href="https://en.wikipedia.org/wiki/KISS_principle" rel="nofollow noreferrer">Keep It Simple</a>. We should use a single tag for these related series.</p>

<p>I realise the benefits of being able to look up FMA:B rather than FMA, but it gets very complicated quickly - when is something a continuity? do we tag all the Dragonball series and all their movies? </p>

<p>It also opens the floodgates for considering even <em>more</em> tags, consider <a href="https://anime.stackexchange.com/questions/tagged/attack-on-titan-manga" class="post-tag" title="show questions tagged &#39;attack-on-titan-manga&#39;" rel="tag">attack-on-titan-manga</a> , <a href="https://anime.stackexchange.com/questions/tagged/attack-on-titan-anime" class="post-tag" title="show questions tagged &#39;attack-on-titan-anime&#39;" rel="tag">attack-on-titan-anime</a> , <a href="https://anime.stackexchange.com/questions/tagged/attack-on-titan-junior-high" class="post-tag" title="show questions tagged &#39;attack-on-titan-junior-high&#39;" rel="tag">attack-on-titan-junior-high</a> and even <a href="https://anime.stackexchange.com/questions/tagged/attack-on-titan-live-action" class="post-tag" title="show questions tagged &#39;attack-on-titan-live-action&#39;" rel="tag">attack-on-titan-live-action</a>. There may be questions about the series as a whole too. "Why are the titans attacking?" for example.</p>

<hr>

<p>There aren't many questions for most series, the only ones that will benefit are the largest (FMA, is admittedly an example). Otherwise, we have 2 tags for maybe 3 questions (if even). </p>

<p>This also means an increase in the amount of retagging we need to do, the amount of tags we fall behind on season-by-season, etc.</p>

<hr>

<p>I think having less tags, while less convenient for searchers is the more <strong>practical</strong> approach.</p>
 7579: <p>I've appreciated SciFi and Fantasy SE's approach more and more as time goes on. For large franchises like Star Trek and Star Wars, SFF has a single tag for the franchise, and then tags for the specific properties in the franchise. For example, they have a <a href="https://anime.stackexchange.com/questions/tagged/star-trek" class="post-tag" title="show questions tagged &#39;star-trek&#39;" rel="tag">star-trek</a> tag, and then <a href="https://anime.stackexchange.com/questions/tagged/star-trek-tos" class="post-tag" title="show questions tagged &#39;star-trek-tos&#39;" rel="tag">star-trek-tos</a>, <a href="https://anime.stackexchange.com/questions/tagged/star-trek-tng" class="post-tag" title="show questions tagged &#39;star-trek-tng&#39;" rel="tag">star-trek-tng</a>, and so on. Questions about the franchise in general will be tagged with just the franchise tag. Questions about a specific series will have the franchise tag as well as the tag for the specific series.</p>

<p>So in our case, we would have an <a href="https://anime.stackexchange.com/questions/tagged/evangelion" class="post-tag" title="show questions tagged &#39;evangelion&#39;" rel="tag">evangelion</a> tag and then <a href="https://anime.stackexchange.com/questions/tagged/eva-tv" class="post-tag" title="show questions tagged &#39;eva-tv&#39;" rel="tag">eva-tv</a>, <a href="https://anime.stackexchange.com/questions/tagged/end-of-eva" class="post-tag" title="show questions tagged &#39;end-of-eva&#39;" rel="tag">end-of-eva</a>, <a href="https://anime.stackexchange.com/questions/tagged/rebuild-of-eva" class="post-tag" title="show questions tagged &#39;rebuild-of-eva&#39;" rel="tag">rebuild-of-eva</a>. Questions about the franchise as a whole, or which are open to answers drawn from any part of the franchise, can be tagged <a href="https://anime.stackexchange.com/questions/tagged/evangelion" class="post-tag" title="show questions tagged &#39;evangelion&#39;" rel="tag">evangelion</a>. Questions which are additionally focused on a single property would also have a specific tag. E.g. "Why was Asuka designed with red hair?" would be tagged <a href="https://anime.stackexchange.com/questions/tagged/evangelion" class="post-tag" title="show questions tagged &#39;evangelion&#39;" rel="tag">evangelion</a> because Asuka's character design pertains to the entire franchise and not just a specific series. "Why did Asuka say 'Kimochi warui'?" would be tagged <a href="https://anime.stackexchange.com/questions/tagged/evangelion" class="post-tag" title="show questions tagged &#39;evangelion&#39;" rel="tag">evangelion</a> <a href="https://anime.stackexchange.com/questions/tagged/end-of-eva" class="post-tag" title="show questions tagged &#39;end-of-eva&#39;" rel="tag">end-of-eva</a>; this way it shows up in searches for <a href="https://anime.stackexchange.com/questions/tagged/evangelion" class="post-tag" title="show questions tagged &#39;evangelion&#39;" rel="tag">evangelion</a> questions, but it's also obvious that the question pertains to <a href="https://anime.stackexchange.com/questions/tagged/end-of-eva" class="post-tag" title="show questions tagged &#39;end-of-eva&#39;" rel="tag">end-of-eva</a>. This also solves the problem of specific tags that only have two or three questions; while there will be such tags (I don't know that we'll have many questions on <a href="https://anime.stackexchange.com/questions/tagged/eva-angelic-days" class="post-tag" title="show questions tagged &#39;eva-angelic-days&#39;" rel="tag">eva-angelic-days</a>, for instance), the questions will be double-tagged as <a href="https://anime.stackexchange.com/questions/tagged/evangelion" class="post-tag" title="show questions tagged &#39;evangelion&#39;" rel="tag">evangelion</a>, so all the Eva questions can be aggregated when necessary.</p>

<p>While I think this would solve our problem, it has two disadvantages. First, it's high maintenance. We would probably need high rep users to buzz around adding and subtracting tags to make sure that every question conforms to the convention. </p>

<p>Second, we'll have to make up our own names for cases like the 2003 Full Metal Alchemist anime, because the tag would need to be distinct from the main <a href="https://anime.stackexchange.com/questions/tagged/full-metal-alchemist" class="post-tag" title="show questions tagged &#39;full-metal-alchemist&#39;" rel="tag">full-metal-alchemist</a> tag as well as the <a href="https://anime.stackexchange.com/questions/tagged/fma-manga" class="post-tag" title="show questions tagged &#39;fma-manga&#39;" rel="tag">fma-manga</a> tag. I don't particularly like ʞɹɐzǝɹ's solution of adding dates and studios (<a href="https://anime.stackexchange.com/questions/tagged/fma-2003" class="post-tag" title="show questions tagged &#39;fma-2003&#39;" rel="tag">fma-2003</a> or <a href="https://anime.stackexchange.com/questions/tagged/unlimited-blade-works-deen" class="post-tag" title="show questions tagged &#39;unlimited-blade-works-deen&#39;" rel="tag">unlimited-blade-works-deen</a>) as these shows are not commonly known by those titles, which means people will be even more likely to tag incorrectly and make more work for other users. I don't have a better idea, though. </p>
