A data carrying output is an unspendable output containing data. The script type is designated as TxoutType::NULL_DATA.
Declared in <kernel/mempool_options.h>
std::optional<unsigned int> max_datacarrier_bytes = {DEFAULT_ACCEPT_DATACARRIER ? std::optional{MAX_OP_RETURN_RELAY} : std::nullopt};Maximum size of TxoutType::NULL_DATA scripts that this node considers standard. If nullopt, any size is nonstandard.