A digital television (DTV) signal for use in a digital television (DTV) receiver includes an extended text table (ETT) for data services. The ETT includes a header and a message body. The header includes a table identification (ID) extension field which serves to establish uniqueness of the ETT, and the message body includes an extended text message (ETM). The table ID extension field includes a data identification of a data event associated with the ETT. The data identification specifies a unique identification number of the data event, and the ETM provides detailed descriptions of the data event. A section-filtering unit included in the DTV receiver can detect one or more pertinent ETTs in an efficient manner by section-filtering a plurality of ETTs using their PIDs and table ID extension fields.