A human readable textual description of the custom error is available in this property. You can assign a new value if you wish. Reading the property yields the value that was passed in the description argument to the constructor function unless it has been changed since then.
The ECMA standard describes this property as Error.message. Netscape 6.0 claims to be completely compliant and therefore should support this property.
MSIE supports the description property which is functionally identical.