Indicates the mask of cascade ports that are watching this program. There are 4096 bits in all, that is, bit0-bit7 indicates the cascade ports with indexs 1-8(The index of the cascade port is in ascending order in one byte). Each bit indicates whether a cascade port is watching the program. Options: 1. 1 -watching this program 2. 0 -not watching this program or the cascade port does not exist It can indicate 4096 cascade ports.