Incorrect connection when a tree node's id is the single letter "o"

[boboboneX]

Description

If a node's id is named as "o", while having two links leaving this node "o" and points to two other links, i.e.,

        o
       / \
     /     \
    p       k

The rendered result has incorrect connections among nodes o, p, and k. The result is like

 o
 |
 p
 |
 k

Steps to reproduce

1. Follow the minimal example:

graph TD;
    o[o]
    o-->p
    o-->k

2. Check the rendered result
3. Replace the node id "o" with other choices, e.g., "o1", and check the result again.

Screenshots

Expected corrected result:

The incorrect result rendered:

Code Sample

graph TD;
    o[o]
    o-->p
    o-->k

Setup

• Mermaid version: 11.4.1
• Browser and Version: Chrome 133.0.6943.127

Suggested Solutions

• Fix the "o"-id bug, or
• Warn that the letter "o" should not be used as a node ID.

Additional Context

No response

[BambioGaming]

Possible Fix for Issue Using "o" as Node ID

Hello. The issue you are facing can be resolved using instructions from the Mermaid documentation. Based on the documentation, if you are using "o" or "x" as the first letter in a node ID, Mermaid may misinterpret it as a special edge type rather than a node identifier.

Solution

To fix this issue, try one of the following approaches:

1. Add a space before the node ID

graph TD
A--- oB
A--- xB

2. Capitalize the first letter of the node ID

graph TD
A--- OB
A--- XB

In your case, instead of doing this:

You can do this:

Here, the letter o is capitalized

Possible Causes of the Issue

• Mermaid interprets o as a circle edge and x as a cross edge, so nodes starting with these letters may not be treated as valid nodes.
• If "o" or "x" is used at the start of a node ID without spacing or capitalization, Mermaid may fail to render the graph properly.

This behavior is documented in the Mermaid syntax guide, as shown in the attached image.

Let me know if this helps!