# Advanced Users Guide

Most of the features described in this section (with the exception of the PLOT and RGMAP /GREY commands), are available through commands of the GTVL language, which is the command language supporting the facilities offered by the graphic library on which GREG is build. This library may also be accessed directly through other programs.

Subsections

- Greyscale and Color plots
  - Bitmap display of images
  - Filled Areas
  - Bitmap Color Editing
  - Pen Colors
  - Devices and Hardcopies
- Plot Architecture and Multi-Window Capabilities
  - Directories
  - Windows
  - The CLEAR command
  - Plotting Depth