<p>I'm trying to write a RegEx for a code generator (in C#) to determine a proper class or package name of an AS3 class.</p>

<p>I know that class names</p>

<ul>
<li>must start with a letter (capital or otherwise)</li>
<li>any other digit can be alphanumeric</li>
<li>cannot have spaces</li>
</ul>

<p>Is there anything else?</p>

Here are some more valid classes.
Actionscript 3 classes (and packages) must start with a letter, "_", or "$". They may also contain (but not start with) a number.
```
```
public class $Test {}
public class _Test {}
public class test {}
```
```