Well technically both are right. When you look at International Standard for currency codes (ISO 4217) it states all currencies are to begin with X. This is why you may land up seeing XBT or XBC instead of the conventional BTC and BCH we are used to in the crypto world!
Specifically the rule is related to country codes and that X is reserved to not be used by any country:
The use of an initial letter "X" for these purposes is facilitated by the ISO 3166 rule that no official country code beginning with X will ever be assigned. Because of this rule ISO 4217 can use X codes without risk of clashing with a future country code. ISO 3166 country codes beginning with "X" are used for private custom use (reserved), never for official codes. For instance, the ISO 3166-based NATO country codes (STANAG 1059, 9th edition) use "X" codes for imaginary exercise countries ranging from XXB for "Brownland" to XXR for "Redland", as well as for major commands such as XXE for SHAPE or XXS for SACLANT. Consequently, ISO 4217 can use "X" codes for non-country-specific currencies without risk of clashing with future country codes.
Wikipedia - https://en.wikipedia.org/wiki/ISO_4217
Hope that helps someone who was a little confused about all these different tickers used!