This feature allows a traffic broadcast to interupt Tape or CD play with immediate traffic information.
From the CDR-220 owners manual:
The Traffic Program system offers the advantage that current traffic news can be seen and heard despite the fact that Tape or CD are selected. For this purpose, it is essential that a traffic program transmitter is selected in the FM waveband and that the Traffic Program is activated.
If the Traffic Program transmtter is selected, the abbr. "T" appears. Press the TP button and a station search will begin to locate the next station broadcasting the TP identifier.
Download the CDR-220 users manual at:
http://www.beckerautosound.com/pdf_guides/om43-4462.pdf