Editing Paper size (section)

=== PA4 or L4 ===

{| class="wikitable floatright"
|+ Hypothetical PA4-based series
! Name
! mm × mm !! inch × inch !!title="Aspect ratio"| AR
|-
! PA0
| {{size|840|1120|p=8|ar=on}}
|-
! PA1
| {{size|560|840|p=8|ar=on}}
|-
! PA2
| {{size|420|560|p=8|ar=on}}
|-
! PA3
| {{size|280|420|p=8|ar=on}}
|- style="font-weight: bolder"|
! PA4
| {{size|210|280|p=8|ar=on}}
|-
! PA5
| {{size|140|210|p=8|ar=on}}
|-
! PA6
| {{size|105|140|p=8|ar=on}}
|-
! PA7
| {{size|70|105|p=8|ar=on}}
|-
! PA8
| {{size|52|70|p=8|ar=on}}
|-
! PA9
| {{size|35|52|p=8|ar=on}}
|-
! PA10
| {{size|26|35|p=8|ar=on}}
|}

A transitional size called '''PA4''' ({{convert|210|×|280|mm|inch|2|abbr=on|disp=or}}), sometimes dubbed '''L4''', was proposed for inclusion into the ISO 216 standard in 1975. It has the height of Canadian P4 paper (215&nbsp;mm&nbsp;× 280&nbsp;mm, about {{frac|8|1|2}}&nbsp;in&nbsp;× 11&nbsp;in) and the width of international A4 paper ({{convert|210|×|297|mm|inch|2|abbr=on|disp=or}}), i.e. it uses the smaller value among the two for each side. The table shows how this format can be generalized into an entire format series.

The PA formats did not end up in ISO 216, because the committee decided that the set of standardized paper formats should be kept to the minimum necessary.{{citation needed|date=December 2016}} However, PA4 remains of practical use today. In [[landscape format|landscape]] orientation, it has the same 4:3 aspect ratio as the displays of traditional TV sets, some [[computer displays]] (e.g. the [[iPad]]) and [[data projector]]s. PA4, with appropriate [[margin (typography)|margin]]s is, therefore, a good choice as the format of presentation slides.

As a compromise between the two most popular paper sizes globally, PA4 is used today by many international magazines, because it can be printed easily on equipment designed for either A4 or US Letter. That means (in practice) it has turned out to be not so much a paper size as a page format. Apple, for instance, requires this format for digital music album booklets.<ref>{{cite web |url=https://help.apple.com/itc/videoaudioassetguide/#/itc585697a99 |title=Music Digital Booklet Profile | website=iTunes Video and Audio Asset Guide |author=Apple iTunes Store |date=2019}}</ref>

The size 210&nbsp;mm × 280&nbsp;mm was documented in the Canadian standard CAN2-200.2-M79 "Common Image Area for Paper Sizes P4 and A4".<ref>{{cite web |url=http://www.scc.ca/en/standardsdb/standards/2464 |title=CAN2-200.2-M79: "Common Image Area for Paper Sizes P4 and A4" |archive-url=https://web.archive.org/web/20170907123539/http://www.scc.ca/en/standardsdb/standards/2464 |archive-date=7 September 2017 |date=1 April 1979}} (NB. Withdrawn 1 March 2012.)</ref>