Re: [groff] mark/lineup in eqn

[John Gardner]

I'm just gonna blurt out that I can't follow a word of this without a
visual. =(

On 2 May 2018 at 07:34, Doug McIlroy <address@hidden> wrote:

> Sorry that my previous post was truncated. Here's what
> I meant to say:
>
> Fellow groffers, what do you think of generalizing the application
> of "mark" and "lineup" in eqn to work in columns and piles as
> well as in separately displayed equations.
>
> A typical use of mark and lineup is to align = signs in
> a sequence of equations. If the = signs signify steps of a
> derivation, the equations should obviously be connected,
> as in a pile. Displaying them separately, each with its
> own EQ-EN, spreads them out vertically. One can play
> with number registers (e.g. PD and DD in -ms) to try
> to get the pile-like resultts, but it would much cleaner
> if that could happen for free.
>
> There is even a situation that EQ-EN can't handle, but
> piles could:
> .EQ L
> xhortid mark = expression1
> .EN
> .EQ
> longidentifier lineup = expression2
> .EN
> The marked place doesn't leave room for the subsequent
> lineup. Piles, being typeset as a whole, would be
> immune to this trouble.
>
> Doug
>
>