Plot Features:
- A feature is a single element of data rendered on a plot.
  - Features can include: boxes, ellipses, points (with various symbols), lines, etc.
  - Features can be added to PLOT with the FEATURE command.
- There are several types of features; a few of them include:
  Box
  
  A rectangular box with center at (x,y) and length/height (dx,dy).
  
  Elps (Ellipse)
  
  Draws an ellipse.
  
  HLine / VLine
  
  Draws horizontal/vertical lines.
  
  Symbol
  A point rendered with one of the various symbols, including:
```
CROSS   - A 'x' symbol.       TRIANGLE  - A triangle symbol.
PLUS    - A '+' symbol.       UTRIANGLE - A triangle (up).
STAR    - A '*' symbol.       DTRIANGLE - A triangle (down).
CIRCLE  - A circle symbol.    RTRIANGLE - A triangle (right).
SQUARE  - A square symbol.    LTRIANGLE - A triangle (left).
DIAMOND - A diamond Symbol.   ASCII-<s> - An ASCII string <s>.
DOT     - A small dot/pixel.  ARROW     - A block arrow.
AERO    - An airplane symbol.
```
  Symbols have a number of options, including size, fill/no-fill, rotation, etc.
- A complete list of the feature types and a complete list of symbols is included in the FEATURE explain file.
- A plot can have many different features.
  - Features are not necessarily homogeneous.
  - Attributes of different features may vary greatly.
  - Features typically have a large amount of variability while elements in a layer are usually homogeneous.
  - Features can be placed in Feature Groups for ease in adjusting similar Features and to have them be displayed in a tree type format with the MMB menu.
  - One of these Features can be designated as an "Elastic Feature", allowing it to be selected and then stretched or moved.
- A LayerDrawable can also have Features.
  - These are listed in the MMB under the Layer.
  - These Features can also be placed in Feature Groups.
- Like layers, it is possible to create your own feature types.
- For more details see the FEATURE explain file or see %test_feature in the test area of SYS.

Don't Make This Mistake:
Take care when sizing features. The type Symbol uses Pixel-Size (i.e. feature is the same size on screen regardless of zoom level), others use Real-World-Coordinates (i.e. feature zooms in relation to the plot).