The transitional paper size formats consist of the PA Series and the F Series. The PA Series proposed to be included into the ISO 216 standard in 1975. They were rejected by the committee who decided that the number of standardised paper formats should be kept to a minimum. However this series is still used today, in particular PA4 (or L4). Its width is that of the ISO standard A4, and height of Canadian P4 (210mm x 280mm). The PA4 format can easily be printed on equipment designed for A4 or US Letter size, which is why it is used by many international magazines, and is a good solution as the format of presentation slides. PA4 is more of a page format than a paper size. It has a 4:3 aspect ratio when in landscape orientation.
In Southeast Asia, a common size used is the non-standard F4. The longer side is 330mm, which is the same as the British Foolscap. The shorter side is 210mm, which is the same as the ISO A4. The F4 is occasionally known as (metric) Foolscap or Folio.