Hi Ane

If by "default value" you mean the keyword used in many places in the input files, like the properties on the atmospheric input file (precipitation, relative humidity, etc), then, the answear is no.
The "default value" that I described above is used only if the data for the property is not given by a file (grid data, hdf, timeseries, etc).
When you use a file as input to the property, lets say a grid data, each cell must have a value.
If you are saying to mohid to delineate the basin (on the basin geometry file), then it will do the simulation looking only for the cells inside the basin and will ignore all the cells that falls outside it. If you are not delieating the basin, than, if I'm not mistaken, you can use the topography grid data to tell to mohid what cells you want to use or not. I think the value to tell that a cell will not be used is -99. Usually will be the value set by the FILL_VALUE keyword in the grid data file.
When you create your grid data from a shape file, using mohid studio, there is an option to you to set the fill value of the grid data. I think it's set to -99 by default, but I'm not sure. The mohid studio will set all cells that fall off the poligons to this value.
So, depending on what you're doing, you need to pay more attention to what value you will use as fill value when constructing a grid data from a shape file, or you may need to edit manually these values to the ones you think are approprietade.
