// comments not parsed

[PlanetEarthSoftware]

If a dot file to be parsed has a // comment in it, it is rejected.
Spec: https://graphviz.org/doc/info/lang.html#comments-and-optional-formatting
The dot program parsed // comments ok.
/* */ comments are also supported by the dot language.

7.dot.zip

[PlanetEarthSoftware]

Dot also supports C style /* */ comments.