@param s kstring to write into @param n total number of items in @p a (<= 0 to encode BCF_BT_NULL) @param a input data to encode @return 0 on success; < 0 on error
See Implementation
@param s kstring to write into @param n total number of items in @p a (<= 0 to encode BCF_BT_NULL) @param a input data to encode @return 0 on success; < 0 on error