Import Overlay The Import Overlay command displays a Windows Open dialog box. This command imports values in a tab delimited text file into the current overlay. The first and second lines of the file must contain the number of columns and rows, respectively, of the data in the text file. No warning message is displayed. Importing will replace all values in the overlay. The text file must have the same number of rows and columns as the model grid. Consult Chapter 4 for more information on importing data.