Alt vs alt? Any difference?

Hello guys,

A friend told me that there was a difference in using the terms “Alt” vs “alt” when it comes to UML. I have heard of using “alt” to describe combined fragments on a sequence diagram, but never of using “Alt” in any formal sense. According to him, “Alt” (capitalized) is a formal term for alternative flows and one should know this as part of knowing UML.

As he is only a student (as I am too) can someone clarify this issue? Is using the terms “Alt” and “alt” part of the formal UML language?

Thanks for your response

Modellers can choose to extend UML for their models as they see fit to assist in describing the system they’re trying to model. If that’s the case, the document containing the extensions usually make it clear how UML is extended and how to interpret these extensions.

Having said that, the argument in question is regarding the language specification of UML[/url]. Whenever a question is brought up about language specification, I like to refer back to the specification document (but I really wish OMG posted these in HTML format for easier linking, oh well). If you look at page 470 of the [url=]language specification, you’ll see they mention Alternatives and the alt operator. Nowhere in this document do I see a mention of distinguishing the capitalisation of alt with different semantics.

I can’t say I’m a master of UML so if I missed something, please let me know. Hope that helps though.

If you are referring to alternative flows in an activity diagram, “Alt” or “alt” have no place there. Also, I don’t think there are any semantic variation points based on capitalisation anywhere in the specification.