'BTC' is the expected form in requests, whereas requests with symbol field 'Btc' or'btc' will fail.All market symbols are capitalized, except for markets with abbreviated numerical prefixes such as
'kBONK' and 'kPEPE' , which have the prefix in lower-case. Requests containing symbol fields such as 'KBONK', 'kbonk', or 'kBonk' will fail.