[NalNezumi]

The one solution that works for me is to color code each arrow and at the top left of the diagram add a legend that describe what each colored arrow represent.

This way sometimes the color can describe control, data, and sometimes even teams expected to implement this arrow by color coding teams.

The latter is very helpful for cross team meetings to make each group focus on the part of the diagram that will affect them the most, and give pointed feedback to assumptions and lack in specs

[orthoxerox]

One company I worked for solved this by agreeing on "triangle-headed arrow ⭢ means control, barbed arrow 🡒 means data" and putting this into the legend. "Calls REST endpoint to get customer data" would then be a double-headed arrow.

[SoftTalker]

Colors are not an adequately accessible differentiator.

[thomas-mc-work]

Why not?

[yzydserd]

color vision deficiency

[ellyagg]

Use an accessible color palette