I've noticed that they occasionally have characters that are available in unicode, but are not part of the characters that are available on a 105-key keyboard with or without the shift key.
THe most common one I see is the integral symbol that used to be used as an S. On very rare occasions I see characters like:
¡™£¢∞§¶•ªº–≠œ∑®†¥øπ«åß∂ƒ©˙∆˚¬…æΩ≈ç√∫˜µ≤≥÷⁄€‹›fifl‡°·‚—±Œ„´‰ˇÁ¨ˆØ∏»ÅÍÎÏ˝ÓÔÒÚƸ˛Ç◊ı˜Â¯˘¿