memoir: Understanding the default margins

Here is a MWE illustrating the margin-setup of memoir:

\documentclass{memoir}
\usepackage{lipsum}

\begin{document}
\chapter{1}
\lipsum

\chapter{2}
\lipsum
\end{document}


The first page of the document is shown below. As you can see, the margin at the left-hand side A is narrower than the margin at the right-hand side B. However, the spine of the book will be at side A, which seems wrong to me as this means that the edge margin will be much wider than the spine margin when the book is opened.

So my question is: What is the idea behind memoir's default margins? Wouldn't it be more correct to have them inverted such that the spine margin would be similar to the edge margin when the book is opened?

• This is typesetting tradition. Have a look at mirrors.dotsrc.org/ctan/info/memdesign/memdesign.pdf, it is written by the author of memoir where is looks at printing tradition. Actually, often in a two page design you would have when a left and a right hand page lay side by side, B A A B, and 2A = B. – daleif Jul 10 at 7:43
• @daleif Thank you, Leif. So when writing a book using memoir and using the above MWE, is it necessary to tweak the margins manually, or will it by default satisfy that 2A = B? – Tyler D Jul 10 at 7:47
• Nowadays there are no strict rules, you just do what you like the best. We often keep in mind what the document is going to be used for. If it is going to be read online, we may set A=B for a better viewing experience. Could of course make two versions but we often don't. Note that when a document is binded (correct word?), aka glued, have a spiral bag or what ever, you'll loose some of A so it will appear as if A < B. – daleif Jul 10 at 7:55
• Note if you add \typeoutlayout in the preamble the layout is written to the log (the unit can be changed, see the memoir manual). Typically you'd use \checkandfixthelayout which automatically runs \typeoutlayout – daleif Jul 10 at 7:58

As daleif said look at memdesign.pdf (> texdoc memdesign). That shows some 32 different page layouts from several countries from 1523 to today, which can all be replicated within memoir. But, generally speaking the spine margin is half the outer margin so that when a book is opened the outer margins and the inner margin are equal. The memoir class provides 3 extra page layouts, \medievalpage, \isopage and \semiisopage, in addtion to the standard LaTeX layout (see section 2.10 Predefined layouts in the manual (> texdoc memoir)).