Category:Host colors

The 3270 data stream protocol defines a set of 16 colors:

Neutrals
Neutral Black and Neutral White have somewhat confusing names, but an important purpose. The names are based on a typical 1970's computer display having light-colored text on a dark background. Neutral White is the default foreground color. Neutral Black is the default background color.

The actual colors rendered by these symbolic Host Colors varies with the type and mode of the display. On a display in white-on-black mode, Neutral Black really is black, and Neutral White really is white. But on a display in black-on-white mode, or on a printer, Neutral Black is white, and Neutral White is black.

The practical use of these "neutral" colors is that a host can specify Neutral White text, and be guaranteed that it will be visible against the background -- as opposed to specifying White text, which would disappear on a printed page. Similarly, it can specify Neutral Black as the background, and be guaranteed it will get the default background color.

NVT colors
The 8 basic colors defined by the NVT mode SGR control code are mapped onto Host Colors according to the table above.