I would guess that 16 columns (0 to F) would have meant that some of the complex characters would have been too small to be easily readable.

Cheers, Si

I'm not sure I understand what you mean, but I'm certain that I wasn't particularly clear myself... If you look at, say Emoticons, and Misc Symbols... If you mean what I think you do, I don't think these tables would need to scaled-down to to facilitate a different orientation. Misc symbols is a 16x16 grid, and prints with enough detail to be referenced.

...

Tradition, maybe. The ECMA charset specs are arranged this way, too.

As good a reason as any I suppose. Thanks.

The Unicode Standard book is portrait format, so it made sense to organise the charts that way, especially since many writing systems or symbol sets only require a few columns.

A practical reason, if a tad off beat for those of us that never learned vertical reading.

Si answered the question.
What else is there to discuss?

(If the 16 rows were to be reconfigured as 16 columns, same size cells, plus header, there would be considerably less margin at left and right.)