Part of the Knowledge Curation series.

A while ago a client asked me to look at some process diagrams which had been created for them by a well-known consultancy.

They we recognizably processes: they had a start and an end, some swim-lanes, and some activities. But some of the activities were blue, and some red.  A a few were purple.

silly coloured process

What’s the difference between these colored activities” asked my client. “Are they important?

I hope not” was my reply.

There was no key to tell the reader what the colors meant. (But that was OK, because the consultants said they would be happy to come back and explain it all – for only USD1500/day.)

And that’s a shame really, because the original authors clearly had a plan in mind when they chose the colors: they were genuinely trying to use those colors to convey information to the reader.

So what do we think about color in models? And for that matter, shapes?

If the purpose of model curation is to convey information, then anything which does that is obviously good. But is more of it better?

In this article, I’ll skip the ‘develop the need’ stage (you know it anyway) and go straight to some suggestions:

  • Use color – but carefully
    • Pale colors. If I have a criticism of the diagram above, it’s that the colors are a too bright – distracting
    • Make it as easy as possible for your modellers to stay consistent to your color scheme
    • EVERY diagram MUST have a legend. No arguments about this
    • Don’t be afraid to invent your own – so long as you tell everyone WHAT and WHY.
  • Use shapes as well.
    A minority of modelling languages have  two styles for their shapes. ‘Rectangle’ , and ‘not rectangle’. For example, here is an Archimate 3 diagram:


It’s a fairly dull diagram, but according to Archimates (sic) it’s full of meaning.

But using the ‘alternative’ notation (which one Archimate luminary described to me as ‘childish’) it would look like this:


A fraction more readable.

But add color as well (I know that Archimates use color for showing layers, but that’s only because lots of their diagrams are ‘look at me’ diagrams):


I think this is a good deal more readable.

So that’s it: use color, shape, positioning on the page, songs, modern dance, free chocolate: whatever it takes to get the information across.

And no technique – used thoughtfully – need be ‘childish’.

About the Author Ian Mitchell

Ian Mitchell is a business analyst and software developer. He's been using UML since before it was UML, and has managed teams of BAs all over the place. He also teaches UML and BPMN, and writes the eaDocX document generator for the Sparx EA tool.


  1. In the early days of UML Pete Coad wrote a good book about UML modelling including the use of colour. It can be used as a kind of ‘stereotype’ – i.e. used to indicate something significant, providing that significance is explained in a key.

    For example in a process flow diagram I might use colour in a couple of ways.
    1) to highlight the ‘happy path’
    2) to indicate the level of IT support (completely manual, actor using IT in the task, completely automated)

    Of course that isn’t much use if you only have B&W printers!

  2. …and I have that very book right here!
    “Java Modelling in Color with UML” ISBN 0-13-011510-X.
    Probably the definitive work on the subject, but they only had UML to deal with – we now have all the other ‘MLs’ as well, which makes it all the more relevant.

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