The original amscd package provides a CD environment that emulates the
commutative diagram capabilities of AMS-TeX version 2.x. This means that only
simple rectangular diagrams are supported, with no diagonal arrows or more
exotic features. This enhancement package implements double ("fat"), dashed,
and bidirectional arrows (left-right and up-down), and color attributes for
arrows and their annotations. The restriction to rectangular geometry remains.
This nevertheless allows the drawing of a much broader class of
"commutative-diagram-like" diagrams. This update, 2.2x of 2019-07-02, fixes the
dashed-arrows parts placement bug, and adds the package option 'lyx', for use
with lyx to prevent conflict with the already loaded amscd. The packages xcolor
and graphicx are made required.
