When an exception is thrown, a throw operand is passed. The type of the throw operand determines which handlers can catch it. The Essential Math Module uses the following hierarchy for throw operands:

This hierarchy assumes the presence of class xmsg, nominally provided by your compiler vendor. Class xmsg carries a string that can be printed out at the catch site to give you some idea of what went wrong. This string can be formatted and internationalized as described in the Essential Tools Module User’s Guide chapter on internationalization. If your compiler does not come with versions of xmsg and xalloc, the Rogue Wave classes RWxmsg and RWxalloc can emulate them for you.