Bottom margin vs. descenders question

[Peter Flynn]

On 25/06/2020 16:11, barbara beeton wrote:
[...]
> An even more rigid model followed by traditional typesetting is
> "grid typesetting", in which *all* baselines line up on facing pages.

That's the asumption of most designers, and it's not hard with 
continuous text like a novel, where every page is identical, but 
definitely problematic with anything else.

One critical thing to avoid in metal type is show-through, where the 
impression of the type on the reverse of the paper is visible. One way 
to minimise this (in addition to employing good press operators) is to 
make sure that the lines of type on one side of the paper line up 
EXACTLY with the lines on the other side. It's also true in modern 
(litho) printing, of course: even though it doesn't indent the paper, 
you still need to minimise the darkness being visible when you are using 
paper that isn't very opaque.

> As has often been noted, this is *not* followed by, and is not easy
> to obtain with TeX, especially in the presence of math displays.

I had to do it for display math once, so I invented an environment which 
set the equation, measured it, and output it vertically-centered in a 
vbox to an integer number of lines. Not elegant, but it helped.

Peter