### GWF-NAM

#### Structure of Blocks

_FOR EACH SIMULATION_

```
    BEGIN OPTIONS
      [LIST <list>]
      [PRINT_INPUT]
      [PRINT_FLOWS]
      [SAVE_FLOWS]
      [NEWTON [UNDER_RELAXATION]]
      [NETCDF_MESH2D FILEOUT  <ncmesh2dfile>]
      [NETCDF_STRUCTURED FILEOUT  <ncstructfile>]
      [NETCDF FILEIN  <netcdf_filename>]
    END OPTIONS
```
```
    BEGIN PACKAGES
      <ftype> <fname> [<pname>]
      <ftype> <fname> [<pname>]
      ...
    END PACKAGES
```

#### Explanation of Variables

##### Block: OPTIONS

  * `list` is name of the listing file to create for this GWF model.  If not specified, then the name of the list file will be the basename of the GWF model name file and the '.lst' extension.  For example, if the GWF name file is called "my.model.nam" then the list file will be called "my.model.lst".

  * `PRINT_INPUT` keyword to indicate that the list of all model stress package information will be written to the listing file immediately after it is read.

  * `PRINT_FLOWS` keyword to indicate that the list of all model package flow rates will be printed to the listing file for every stress period time step in which "BUDGET PRINT" is specified in Output Control.  If there is no Output Control option and "PRINT_FLOWS" is specified, then flow rates are printed for the last time step of each stress period.

  * `SAVE_FLOWS` keyword to indicate that all model package flow terms will be written to the file specified with "BUDGET FILEOUT" in Output Control.

  * `NEWTON` keyword that activates the Newton-Raphson formulation for groundwater flow between connected, convertible groundwater cells and stress packages that support calculation of Newton-Raphson terms for groundwater exchanges. Cells will not dry when this option is used. By default, the Newton-Raphson formulation is not applied.

  * `UNDER_RELAXATION` keyword that indicates whether the groundwater head in a cell will be under-relaxed when water levels fall below the bottom of the model below any given cell. By default, Newton-Raphson UNDER_RELAXATION is not applied.

  * <span style="color:red">`NETCDF_MESH2D` keyword to specify that record corresponds to a layered mesh netcdf file.</span>

  * <span style="color:red">`NETCDF_STRUCTURED` keyword to specify that record corresponds to a structured netcdf file.</span>

  * `FILEOUT` keyword to specify that an output filename is expected next.

  * <span style="color:red">`ncmesh2dfile` name of the netcdf ugrid layered mesh output file.</span>

  * <span style="color:red">`ncstructfile` name of the netcdf structured output file.</span>

  * <span style="color:red">`NETCDF` keyword to specify that record corresponds to a netcdf input file.</span>

  * `FILEIN` keyword to specify that an input filename is expected next.

  * <span style="color:red">`netcdf_filename` defines a netcdf input file.</span>

##### Block: PACKAGES

  * `ftype` is the file type, which must be one of the following character values shown in table ref{table:ftype-gwf}. Ftype may be entered in any combination of uppercase and lowercase.

  * `fname` is the name of the file containing the package input.  The path to the file should be included if the file is not located in the folder where the program was run.

  * `pname` is the user-defined name for the package. PNAME is restricted to 16 characters.  No spaces are allowed in PNAME.  PNAME character values are read and stored by the program for stress packages only.  These names may be useful for labeling purposes when multiple stress packages of the same type are located within a single GWF Model.  If PNAME is specified for a stress package, then PNAME will be used in the flow budget table in the listing file; it will also be used for the text entry in the cell-by-cell budget file.  PNAME is case insensitive and is stored in all upper case letters.

#### Example Input File
```
    # This block is optional
    BEGIN OPTIONS
      PRINT_INPUT
      PRINT_FLOWS
      SAVE_FLOWS
    END OPTIONS
    
    # List of packages.  List can be listed in any order.
    BEGIN PACKAGES
      IC6           bcf2ss.ic
      NPF6          bcf2ss.npf
      WEL6          bcf2ss.wel  WEL-COUNTY
      RIV6          bcf2ss.riv
      RCH6          bcf2ss.rch
      OC6           bcf2ss.oc
      DIS6          bcf2ss.dis
    END PACKAGES
```