Symbolic equation labels

In short notes, classroom assignment, and tests it is often convenient to label an equation by a symbol; e.g.
\begin{symboleqn}{(*)} x^n + y^n = z^n. \end{symboleqn}
This can be accomplished by the sequence
\begin{symboleqn}{(*)}
x^n + y^n = z^n.
\end{symboleqn}
Any text can replace the (*), but keep in mind that it will be set in math mode. Equations generated by symboleqn cannot be labeled; any references must be constructed explicitly.

Since asterisks are a favorite symbol in this connection, let me note some of the pitfalls. Always set (*) in math mode thus: $(*)$. If you enter (*), you will get (*), with the asterisk too high. To get (***) enter $(*{*}*)$. The braces keep TEX from treating the inner asterisk as an operator.