TikZ-CD – Drawing Parallel Arrows Without Heads

Question

The official tikz-cd is available here.

On page 3, one reads:

The following list shows all available arrows.

I tried all items in the list, and got error messages for the three items: dash, equal, and mapsfrom.

All the other items worked perfectly.

As pointed out by egreg in his answer to this question, one can use [-] instead of [dash].

I tried to use [=] instead of [equal], but it didn't work.

I got a not very good-looking mapsfrom using [<-|].

Of course I'd be delighted to have an explanation, but, above all, I'd like to find a way of obtaining the equal and mapsfrom arrows (mainly the equal one).

Here is a Minimal Working Example:

\documentclass{article}
\usepackage{tikz-cd}
\begin{document}
\[
\begin{tikzcd}
X \ar[equal]{r} & Y
\end{tikzcd}
\]
\end{document}

Answer 1

This is what I get (tikz-cd version 0.3c, tikz version 2.10) from

\documentclass{article}
\usepackage{tikz-cd}
\begin{document}
\[
\begin{tikzcd}
X \ar[equal]{r} & Y \ar[mapsfrom]{r} & Z
\end{tikzcd}
\]
\end{document}