The ETM_location field denotes whether there is an extended text message for the channel (Channel Extended Text table or CETT), event (Event Extended Text table) or data event (Data Extended Text table).
valid ETM_location values
|0 / 0x00||No Extended Text Message|
|1 / 0x01||Extended Text Message is located in the physical transmission channel carrying this PSIP.|
|2 / 0x02||Extended Text Message is located in the physical transmission channel specified by channel_tsid. (Note: this is to be used when channel_tsid is different from the tsid carrying the PSIP.|