when import data, if we need not show time column and use append col import mode, we need check if wks has x column. It will return true, if wks is not empty AND has X column.
bool wks_has_x( Worksheet & wks )
True for worksheet has an X column and not empty; otherwise false.
Worksheet wks = Project.ActiveLayer();
if(wks_has_x( wks ))
printf("Active worksheet has X column!");