Lossy compressors don't have the same constraints as a lossless compressor. If you data your input, compress it, and then decompress it, the output is not identical to the input. This allows the compressor to potentially compress the data far more than even the ideal lossless compressor hypothesized above.
The question mark (?), also known as the interrogation point, query, and eroteme, is a punctuation mark that indicates an interrogative clause, or phrase in many languages. The question mark is not used for indirect questions.
Pound sign is also a term sometimes used for the number sign, #, in the United States, and sometimes in Canada; (in Canada however, the symbol is generally only used for number, and its being referred to as pound is a much more recent borrowing from the American telephone system and limited to telephone use alone.