вставлять диаграммы химической структуры в документы groff (embed chemical structure diagrams in groff documents)
Описание (Description)
chem produces chemical structure diagrams. Today's version is
best suited for organic chemistry (bonds, rings). The chem
program is a groff preprocessor like eqn, pic, tbl, etc. It
generates pic output such that all chem parts are translated into
diagrams of the pic language.
If no operands are given, or if file is '-', chem reads the
standard input stream. -h and --help display a usage message,
whereas -v and --version display version information; all exit.
The program chem originates from the Perl source file chem.pl.
It tells pic to include a copy of the macro file chem.pic.
Moreover the groff source file pic.tmac is loaded.
In a style reminiscent of eqn and pic, the chem diagrams are
written in a special language.
A set of chem lines looks like this
.cstart
chem data
.cend
Lines containing the keywords .cstart and .cend start and end the
input for chem, respectively. In pic context, i.e., after the
call of .PS, chem input can optionally be started by the line
begin chem and ended by the line with the single word end
instead.
Anything outside these initialization lines is copied through
without modification; all data between the initialization lines
is converted into pic commands to draw the diagram.
As an example,
.cstart
CH3
bond
CH3
.cend
prints two CH3 groups with a bond between them.
If you want to create just groff output, you must run chem
followed by groff with the option -p for the activation of pic:
chem [file ...] | groff -p ...
