The constants in a few other comments above appear to be inaccurate. Here are some more official references that seem quite hard to search.
The "type" attribute: https://dev.mysql.com/doc/internals/en/com-query-response.html#column-type
The "flags" attribute: https://github.com/google/mysql/blob/master/include/mysql_com.h#L133
In addition, all attributes are explained on the COM_QUERY_RESPONSE page too: https://dev.mysql.com/doc/internals/en/com-query-response.html#column-definition