The set of values your TV_ttf_display_function may return to TotalView is defined in the enum TV_ttf_format_result given in the file tv_data_display.h included with your distribution of TotalView. These values are:

Your function should return this value if it has successfully formatted the data and successfully registered its output using TV_ttf_add_row.

As TV_ttf_format_ok but indicates that the output may be subject to type elision (see below).

Return this if your function was unable to format the data. When displaying the data, TotalView will indicate that an error occurred.

Use this to have your function tell TotalView to display the raw data as it would normally do, that is, as if there were no TV_ttf_display_type present for that type.

As TV_ttf_format_raw. In addition, this value tells TotalView never to call the display function again.