It can be cumbersome and impractical to try to maintain your data in a LINGO model file. In most cases, your model's data will reside externally in files, spreadsheets, and databases. Also, a solution generated by LINGO is of little use if you can't export it to other applications. For these reasons, LINGO has many methods to assist you in moving information in and out of the application. The primary focus of this section is to illustrate how to move data in and out of LINGO through the use of text based ASCII files. In Interfacing with Spreadsheets, we will look at using spreadsheets and, in Interfacing with Databases, we will illustrate the use of databases for maintaining your model's data.