Regular followers of this blog will know that in the middle of the month, I publish a "What is ....? post. The article covers various aspects of paper, printing and finishing in greater depth. However, many of these subjects are complex, so these posts are only intended to be a brief introduction to the topic.
What is ...the way to describe Portrait/Landscape?
The names Portrait and Landscape are taken from the world of painting and art. Portraits are painted with the short edge at the top and longer edge at the sides. Landscape pictures have an long edge at the top and short edges at the sides
the first dimension given determines the depth of a given publication. Therefore 297x210mm indicates an A4 portrait and 210x297mm indicates an A4 landscape.
I am unable to find any reference material that backs this up but it is certainly well entrenched in the psyche of printers. Personally I think it is better to actually state whether the desired format in words rather than relying on a potentially misleading way of doing things - but maybe that just me!