Stroke order explanation for 凸 and 凹


The correct stroke order of `凹` is apparently:

![traditional stroke order of 凹](https://i.stack.imgur.com/p2BWc.jpg)

Is there any reason for this order? Why, for example, would one not write the
vertical `|` stroke to the bottom right directly after the 3rd stroke,
effectively reducing the stroke count to 4?

Same question for `凸`, the correct stroke order seems to be one of these:

![two possible stroke orders for 凸 from a
dictionary](https://i.stack.imgur.com/Vf40L.jpg)

(left: 新漢語林【しんかんごりん】, right: 新選漢和辞典【しんせんかんわじてん】)

So how did people come up with these stroke orders?




## 凹

The stroke order you mentioned is the correct one indeed. It can be found in
the 新漢語林【しんかんごりん】, for example.

[This page, _kakijun_](http://kakijun.jp/page-ms/0517200.html), offers an
explanation for the stroke order:

Traditionally, ie. based upon the 字彙【じい】 and 康熙【こうき】 dictionaries, `凹` is
categorized under the 凵【かんにょう】 radical, so this part is written individually.
`凵` is written with | stroke to the right last, as in `凶` or `画`. The
remaining part is written following the general principles left-to-right and
top-to-bottom.

Remember that although there are rules and guidelines, the exact stroke order
can involve some arbitrariness. The page linked above also mentions an
alternative, more logical stroke order based upon the character's shape.

![alternative stroke order for 凹](https://i.stack.imgur.com/tK5eL.gif)

## 凸

Same reason as above, it is categorized under the `凵` radical, and thus the
top part is written indiviually. As can be seen in the image you posted, there
is some variation to how the top part can be written, although the stroke
order to the left with the vertical `|` stroke first seems to be more common,
it is also the stroke order indicated by the 新漢語林.

## 卍

[This entry on
_akatsukinishisu_](http://www.akatsukinishisu.net/kanji/dekoboko.html)
mentions that there are some people writing `凸` and `凹` with one stroke as
well. It also notes that uniquely shaped `卍`, categorized under the 十(じゅう)
radical, is written with the `十` part individually as well, giving some
credibility to the explanation for `凸` and `凹`.

![stroke order 卍, variation 1](https://i.stack.imgur.com/OgVWC.gif) ![stroke
order 卍, variation 2](https://i.stack.imgur.com/K4Tvo.png)




## 凹

The stroke order you mentioned is the correct one indeed. It can be found in
the 新漢語林【しんかんごりん】, for example.

[This page, _kakijun_](http://kakijun.jp/page-ms/0517200.html), offers an
explanation for the stroke order:

Traditionally, ie. based upon the 字彙【じい】 and 康熙【こうき】 dictionaries, `凹` is
categorized under the 凵【かんにょう】 radical, so this part is written individually.
`凵` is written with | stroke to the right last, as in `凶` or `画`. The
remaining part is written following the general principles left-to-right and
top-to-bottom.

Remember that although there are rules and guidelines, the exact stroke order
can involve some arbitrariness. The page linked above also mentions an
alternative, more logical stroke order based upon the character's shape.

![alternative stroke order for 凹](https://i.stack.imgur.com/tK5eL.gif)

## 凸

Same reason as above, it is categorized under the `凵` radical, and thus the
top part is written indiviually. As can be seen in the image you posted, there
is some variation to how the top part can be written, although the stroke
order to the left with the vertical `|` stroke first seems to be more common,
it is also the stroke order indicated by the 新漢語林.

## 卍

[This entry on
_akatsukinishisu_](http://www.akatsukinishisu.net/kanji/dekoboko.html)
mentions that there are some people writing `凸` and `凹` with one stroke as
well. It also notes that uniquely shaped `卍`, categorized under the 十(じゅう)
radical, is written with the `十` part individually as well, giving some
credibility to the explanation for `凸` and `凹`.

![stroke order 卍, variation 1](https://i.stack.imgur.com/OgVWC.gif) ![stroke
order 卍, variation 2](https://i.stack.imgur.com/K4Tvo.png)

