The model file used in Visual OTTHYMO v1.0.x, OTTHYMO-89/INTERHYMO and OTTHYMO-83 is in similar text file format. It may have the extension of ott, dat or txt. These files can be imported as a new scenario to current project with menu File -> Import -> Import Scenario (Otthymo 89). As the location of the hydrologic objects are not specified in the model file, the objects will be arranged from top to bottom. The most upstream objects will be located on the top. Their locations can be changed later to represent the shape of the drainage network.

Any commands that are not included in VO5 are ignored during the import. These commands may include COMPUTE VOLUME, PRINT HYD, PLOT HYD, SAVE HYD and ERROR ANALYSIS.