Editing Envelope (section)

=== Japanese sizes ===
Japanese traditional rectangular (角形, ''kakugata'', K) and long (長形, ''nagagata'', N) envelopes open on the short side, while Western-style (洋形, ''yōgata'', Y) envelopes open on the long side.
<!-- ISO C4 is called ''Kaku Koku-sai A4''.-->
The Japanese standard JIS S 5502<ref name="jiss5502">[https://webdesk.jsa.or.jp/books/W11M0090/index/?bunsyo_id=JIS+S+5502%3A2010 JIS S 5502:2010 ''Envelopes'', translated]</ref> was first published in 1964. Some traditional sizes were not kept and some sizes have been removed until its latest edition in 2014, leaving behind gaps in the numeric sequence of designations.

{| class="wikitable sortable"
|+ Japanese envelopes<ref name="pwg"/>
!colspan=2| Format !! Standard !! Dimensions (mm) !! Dimensions (in) !! {{abbr|AR|Aspect ratio}} !! Suitable content format
|-
! Kaku A3 || <!--PWG?-->
| {{no|informal}}
| {{size|320|440|ar=yes}} || A3
|-
! Kaku 0<!--PWG?--> !! K0
| {{yes|not in PWG}}
| {{size|287|382|ar=yes}} || B4
|-
! Kaku 1 !! K1
| {{no|in PWG}}
| {{size|270|382|ar=yes}} || B4
|-
! Kaku 2 !! K2
| {{yes}}
| {{size|240|332|ar=yes}} || A4
|-
! Kaku 20 !! K20
| {{yes|ISO C4}}
| {{size|229|324|ar=yes}} || A4
|-
! Kaku 3 !! K3
| {{yes}}
| {{size|216|277|ar=yes}} || B5
|-
! Kaku 4 !! K4
| {{yes}}
| {{size|197|267|ar=yes}} || B5
|-
! Kaku 5 !! K5
| {{yes}}
| {{size|190|240|ar=yes}} || A5
|-
! Kaku 6<!--no alias in PWG 5101.1--> !! K6
| {{yes|ISO C5}}
| {{size|162|229|ar=yes}} || A5
|-
! Kaku 7 !! K7
| {{yes}}
| {{size|142|205|ar=yes}} || B6
|-
! Kaku 8 !! K8
| {{yes}}
| {{size|119|197|ar=yes}} || salaries, wages
|-
! Chou 1<!--PWG?--> !! N1
| {{no|deprecated}}
| {{size|142|332|ar=yes}} || A4 folded in half lengthwise
|-
!rowspan=2| Chou 2 !! N2
| {{yes|not in PWG}}
| {{size|119|277|ar=yes}}<!--PWG?--> || B5 folded in half lengthwise
|-
!
| {{no|in PWG}}
| {{size|111.1|146|ar=yes}} <!--PWG!--> || 
|-
! Chou 3 !! N3
| {{yes}}
| {{size|120|235|ar=yes}} || A4 folded in thirds
|-
! Chou 30<!--PWG?--> !! N30
| {{no|deprecated}}
| {{size|92|235|ar=yes}} || A4 folded in fourths
|-
! Chou 4 !! N4
| {{yes}}
| {{size|90|205|ar=yes}} || JIS B5 folded in fourths
|-
! Chou 40 !! N40
| {{yes}}
| {{size|90|225|ar=yes}} || A4 folded in fourths
|-
!  !! N6
| {{yes|DL}}
| {{size|110|220|ar=yes}} || A4 folded in thirds
|-
! You 0, You 8 !! Y0
| {{no|deprecated}}
| {{size|136|197|ar=yes}} || ''kyabine'' (cabinet) size photos ({{resx|120 mm|165 mm}})<!--, You 1-->
|-
!rowspan=2| You 1 !! Y1
| {{yes|not in PWG}}
| {{size|120|176|ar=yes}} <!--ISO B6: 125|176 --> ||rowspan=2| C6, You 2<!--; B5 folded in quarters-->
|-
!
| {{no}}
| {{size|118|173|ar=yes}}
|-
! You 2 !! Y2
| {{yes|ISO C6}}
| {{size|114|162|ar=yes}} || A6 ({{resx|105 mm|148 mm}}), Hagaki
|-
! You 3 !! Y3
| {{no|deprecated}}
| {{size|98|148|ar=yes}}  || JIS B7 ({{resx|91 mm|128 mm}})
|-
! You 4 (Chou 31) !! Y4
| {{yes}}
| {{size|105|235|ar=yes}} || A4 folded in thirds ({{resx|99 mm|210 mm}}), You 5
|-
! You 5 !! Y5
| {{no|deprecated}}
| {{size|95|217|ar=yes}}  || A4 folded in fourths ({{resx|74 mm|210 mm}})
|-
! You 6 !! Y6
| {{yes}}
| {{size|98|190|ar=yes}}  || <!--JIS B5 folded in thirds, You 7-->
|-
! You 7 !! Y7
| {{no|deprecated}}
| {{size|92|165|ar=yes}}  || JIS B7
|}