Hi Cdukeprogyny,

Here is a link to the Lucid help article on Diagram as code.

And here is a link to the Mermaid User Guide (also linked in the Lucid article), which includes syntax rules.

If you aren’t able to find what you need there, let me know. I’m not familiar with the functions myself, but I can ask the team who built it to look at your specific problem.

Thanks!

Thank you Lance

I think what I’m seeing can be demonstrated by the following:

C4Component
    title Component diagram for Internet Banking System - API Application

    System(sysA, "System A", "System A")
    System(sysB, "System B", "System B")

    System_Boundary(sysbA, "System Boundary A") {
        Container(conA, "Container A", "Container A")
        Container(conB, "Container B", "Container B")

        Rel_Right(conA, conB, "Rel right")
    }

    Rel_Left(sysA, sysB, "Rel left")
    Rel_Right(sysA, sysB, "Rel right")

The “Rel left” arrow is appearing but Rel right is not and if you change Left to Right or Right to Left on the Rel functions it has no impact to the drawing.

I would expect to see something like this:

but what i see in Lucidchart:

Thanks for all the detail! I tried debugging it a bit as well and couldn’t get it to work and couldn’t find any reason online why it shouldn’t work. Let me ask the right team if this is a bug or if we are doing something wrong.

Alright, I talked to the engineer who worked on it as well as looked around a bit more. As best I can tell, this doesn’t work on Mermaid’s side. When I put the same code into mermaid.live, it gives the same result. I assume this is due to C4 diagrams being experimental with Mermaid generation, which is what we’re using.

From Mermaid’s website:

C4 Diagram: This is an experimental diagram for now. The syntax and properties can change in future releases. Proper documentation will be provided when the syntax is stable.

The best recommendation I have is to represent the relationship in a single line, i.e. “Rel right and Rel left.” Sorry about the inconvenience.

Thanks for looking into this!