A cursor offset represents a position in the 3270 screen buffer as a single value (an offset). The upper left-hand corner of the display is offset 0. On a model 2 with 24 rows of 80-column lines, the last position of the top line is offset 79, and the lower right-hand corner is offset 1919.
Note that unlike row and column coordinates, a cursor offset is always 0-origin.
A cursor offset is called a buffer address in the 3270 data stream protocol.