# [texhax] TeX Queries (1)

Paul Isambert zappathustra at free.fr
Mon Jul 9 19:08:56 CEST 2012

Le 09/07/2012 17:19, Paul Stanley a écrit :
> Hi folks
> A few Tex queries from the TeXBook. I'm looking at the TeX source,
> http://net.ytu.edu.cn/share/%D7%CA%C1%CF/texbook.pdf :

> chapter 1, page 1, paragraph 1:
> English words like technology' stem from a Greek root <elipsis> which
> is an uppercase form of $\tau\epsilon\chi$.^^{TeX (actually \TeX),
> meaning of} ^^|\tau|^^|\epsilon|^^|\chi|
>
> Does ^^{ ... }' signify a margin note?  I'm calling it a margine note
> because it appears separate from the main text on the right edge of
> the page.

The whole situation with ^{...}' deals with the index; it is explained
lines 23907 and following of the sources. (That the expressions are in
the margin is only for proofreading.)

> chapter 2, page 3, paragraph 2:
> In the first place, there are two kinds of <elipsis> that shows up as
> something like {\tt\char'22}, and an apostrophe or right-quote that
> looks like {\tt\char'15} or {\tt\char'23}.
>
> \char' according to some web sources maps numeric values to their
> corresponding unicode characters.  in the above extract the macro is
> separated from the numeric value by an apostrophe. I've seen both a
> grave accent () and a double quote mark (") used in examples on the
> web. Do the symbols declare different things about the number that
> follows them?

The syntax is: \char<number>; and a number can be octal (prefixed with a
single quote) or hexadecimal (double quote), and of course decimal
(unprefixed). For the grave I can't see any usage but denoting a number
via a character, i.e. \a (meaning 97, with the backslash optional in
this case).

By the way, \char<number> simply typesets the character at position
<number> in the font and has nothing to do with Unicode (especially as
legacy TeX knows nothing of Unicode).

> finally, what's the difference between \eject' and \vfil\eject'?  I
> understand \ject' forces a page break.  A \vfil' prefix I hear
> improves/mitigates the visual effect of \ject' in certain circs.
> Unfortunately, the text doesn't explain exactly what form the
> improvmenet takes.  Any clues would be appreciated.

The \vfil means the page will be flushed upwards, unless equivalent or
stronger \vfil's are used elswhere. For instance:

paragraph1

paragraph2

\eject

will create a page with paragraph1 at the top and paragraph2 at the
bottom because the only adjustment possible to fill the page is to
stretch the interparagraph glue; \vfil avoids that.

Best,
Paul

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