Command \umlobject

In a sequence diagram, a “standard” object can be defined with the \umlobject command:

\begin{umlseqdiag}
\umlobject{a}
\end{umlseqdiag}

Both options x and y allows you to place the object in the figure. The argument to give is the label of the object. The node representing the state has a default name, based on a global counter. For practical reasons, when you define a message for instance, you can rename it with the name option. You can give the class name with the class option (empty by default).

\begin{umlseqdiag}
\umlobject[class=A]{a}
\end{umlseqdiag}