It shows where the top left corner of the text is placed.

Oh, and it's also a secondary golden section. The picture was developed by Jan Tschihold when he was trying to find the formula that was used on incunabula.

The diagonal red line where it crosses the diagonal black line indicates the left corner of your type/illustration box, send a horizontal line across and stop at the next diagonal, send a vertical line down until it meets another diagonal etc etc.

It gives the gutter margin. This one looks a bit anemic to me. It might work with a largish book.

or what dsgoen said (i should read before i post)

I generally use this model (in green on my avatar, known as the Villard diagram) to draw my text frame, then round out the margins to whole numbers, raise the top margin a bit, lower the bottom margin somewhat, and, finally, shift the frame 1pica towards the outside edge to account for the binding.

I'll take back, or at least qualify, my comments. I actually do like these proportions for reasonably-sized books (larger than mass-market paperback). I think the size of the gif on my screen (the size of a miniature book) was what set me off.

thanks

Golden ratio and Fibonacci numbers are great start for developing grid, type areas and other.

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golden ratio of passion. sansogno.coastaldisturbance.com

The red line shows that the golden ratio section also accounts for the left corner. The red lines start at the point defined by the golden ratio. It's just making the relationship clear.

For those nice, classical gutter margins: Just make sure the book will be Smythe-sewn. If it is perfect-bound or even notch bound, your readers will be digging the text out of the gutter.

I was trying to explain it to someone else, and as I was doing so, realized the significance of the red line....thanks again

My roommate in college was a huge numbers freak, seriously, he had a man-crush on Fibonacci (and a large poster of him in his room!)

I've always been interested in how the Golden Ratio and Fibonacci's number sequence interacted with elements of design. This is a great example.

Jason, I was wondering what your Avatar was, I could see the Golden Ratio on the left, but hadn't a clue what was represented on the right. Thanks for clearing that up. Is there a link to a larger version somewhere?

Charles, how much do you correct--how much added to the gutter--for the different types of bindings?

That's just freakin sweet looking! Thanks

Ow yeah! Now that's cool :-) Had already been scouting the internet to find a magnified version of your avatar; this just made it 1000x easier :-).

While searching though, I found this: The Typesetting Area (PDF, 216KiB), courtesy The Dutch TeX user group website.

My sketch is just a quick combination of diagrams from a few different sources, mainly Tschichold (The Form of the Book) and Bringhurst, but that PDF looks quite good as well.

http://en.wikipedia.org/wiki/Canons_of_page_construction

I use that somtimes, but usually I have to increase the inside margins quite a bit.
I guess it works if you use a binding method that allows a book to lie open flat.

I think we have a spammer: sunyapeng2006

Every topic he's responded too has been about some World of Warcraft thing.

Yep, it's copied posts from others, reposted with WoW-crap underneath.