Input (grade 11): The name "RC4" is trademarked, so RC4 is often referred to as "ARCFOUR" or "ARC4" (meaning Alleged RC4) to avoid trademark problems.
Output (grade 10): The name "RC4" is trademarked, however. RC4 is often referred to as "ARCFOUR" or "ARC4" (meaning Alleged RC4, because RSA has never officially released the algorithm), to avoid possible trademark problems.