Context: Unicode defines two mapping methods: the Unicode Transformation Format (UTF) encodings, and the Universal Coded Character Set (UCS) encodings. An encoding maps (possibly a subset of) the range of Unicode code points to sequences of values in some fixed-size range, termed code values. The numbers in the names of the encodings indicate the number of bits per code value (for UTF encodings) or the number of bytes per code value (for UCS encodings). UTF-8 and UTF-16 are probably the most commonly used encodings. UCS-2 is an obsolete subset of UTF-16; UCS-4 and UTF-32 are functionally equivalent.

Question: How many mapping methods does Unicode define?
Answer: two

Question: What are the two mapping methods that Unicode defines?
Answer: Unicode Transformation Format (UTF) encodings, and the Universal Coded Character Set (UCS) encodings

Question: What do numbers in the names of the encodings indicate? 
Answer: the number of bits per code value (for UTF encodings) or the number of bytes per code value

Question: What are the most commonly used encodings? 
Answer: UTF-8 and UTF-16

Question: What does UCS stand for?
Answer: Universal Coded Character Set

Question: How many mapping modes does USC have?
Answer: Unanswerable

Question: What maps an encoding?
Answer: Unanswerable

Question: What is the subset of UTF-8?
Answer: Unanswerable

Question: What is functionally equivalent to USC-2?
Answer: Unanswerable

Question: What do the sequences of values indicate?
Answer: Unanswerable