### Plot Basics

The NeXtMidas `PLOT` command plots the following types of files:

- Midas Blue Files - Types 1000, 1999, 2000, 3000, 5000, 5010
- Graphical Images - gif, tif, jpg, png, etc.
- National Geospatial-Intelligence Agency (NGA) Images
- Shape files (*.shp)
- KML files (*.kml)
- GeoJSON files (*.geojson)

The single NeXtMidas command `PLOT` does the same thing as all these X-Midas commands combined: `xplot, xrtplot, xraster, xrtraster` and `xgeoplot`! `PLOT` identifies the file type of the first file and applies the appropriate plot type. The type can be overridden with the `type=` modifier.

The following sections detail a few caveats associated with the NeXtMidas `PLOT` command.

- Layer Stacking Order
- Using Features
- Backing Store
- Macro Interface
- Mouse Interaction in a Plot

##### Stacking Order

By default, layers (or files) are stacked the way they are entered on the command line (first is on the bottom). If Backing Store is used for a layer, that layer(s) is drawn first.

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##### Using Features

See the `FEATURE` explain file.

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##### Backing Store

Backing store is a mechanism where static layers are drawn without recomputation.

- When-to-use:
  Use Backing-store when there are static layers with non-static layers on top. Enabling Backing-store uses more memory and you do not see the static (Backing-stored layer) draw. However, the static layer does not have to be redrawn every time.
- How-to-Use:
  Backing-store is disabled by default, except for LayerPoly (Midas Type 1999) and LayerShape (*.shp) files. Individual layers may have backing-store enabled but it is not be used unless it is turned on at the plot level via the `/ALL` switch or `OPTION=` modifier.
- Default Layer Enabling:
  As mentioned above, individual layers may have backing-store enabled but it is not used unless it is turned on at the plot level. Most layers are candidates for backing-store except for:
  - All Real-Time Layers - Pipe input or forced at the command line.
  - LayerGeo - Draws Geodetic (TDOA/FDOA) lines from state vector data.
  - LayerT5 - Enabled because names and symbols, which often act like features, are frequently drawn.

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##### Macro Interface

`PLOT` (and many NeXtMidas primitives) handle events and send messages to the macro in response to these events. For instance, when the LMB is clicked in a `PLOT` a `MARK` message is sent to the macro. See the `PLOT` explain file for a complete list of messages.

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