[jablan]

Sequence diagrams, as probably most other UML diagrams too, predate UML.

[dragontamer]

The point of UML was never to "invent" new diagrams. The point was to unify all diagrams so that your arrows in one visual-language are compatible with the arrows in another visual-language.

[jhayward]

> Sequence diagrams, as probably most other UML diagrams too, predate UML.

This misses the point of UML, entirely. The point is not that diagramming was invented, it was that it was standardized.

So you don't have to spend half your meeting discussing just exactly what this particular arrow between these two boxes means.

[libria]

Apparently it postdates UML too: there's a sequence diagram tool trending on the front page right now[1].

[1] https://news.ycombinator.com/item?id=26956728

[cratermoon]

I think there's only one kind of diagram that in UML that doesn't have a clear predecessor: the activity diagram. There's a reason it's called the Unified Modelling Language, after all.