The PLOT Command:
- PLOT is typically run with one or more files as an input.
- To input multiple files, separate each file by a bar character (|).
```
nM> plot world.shp|cities.prm
```
- Attributes for each layer can be changed in line with the LAYER={...} qualifier.
```
nM> plot world.shp{TAG=COUNTRIES,LAYER={OPAQ=0,LABEL=NAME}}|&
             cities.prm{LAYER={COLOR=RED}} 
```
  In the above example the qualifiers LAYER={OPAQ=0,LABEL=NAME} tells the plot layer to make the opaqueness zero (i.e. transparent) and to show a label on the readout with the NAME of the country.
- By default layer names are automatically set to match the root name of the file. this can be overridden using the TAG= qualifier.
  - For example: Because of duplicate tags, only one of files shows up.
```
nM> plot world.shp{LAYER={OPAQ=0}}|world.prm
```
  - This will work.
```
nM> plot world.shp{TAG=SHP,LAYER={OPAQ=0}}|world.prm{TAG=PRM}
```
- In order to use messages, one must add the /msgid= switch. (This is discussed more in the module on Macros.)
- The PLOT command takes in a number of command line parameters allowing customization of the plot.
  - Most of these options are settable using reg.<id>.<option>.
  - A few examples:
    - Setting Y-axis limits (Y1, Y2).
```
nM> plot/bg/id=myplot fftdemo.prm Y1=50 Y2=150
```
      or
```
nM> plot/bg/id=myplot fftdemo.prm
nM> set reg.myplot.y1 50
nM> set reg.myplot.y2 150
```
    - Setting the view of a map.
```
nM> plot/bg/id=myplot nxm.sys.dat.world.prm|cities.prm view=MERCATOR
nM> set reg.myplot.view LATLON
nM> set reg.myplot.view GEO
```