3270 models

The x3270 family can emulate any of the following IBM 3270 models: Within the above types, there are a number of variants based on screen size:

Extended data stream support
In addition, there is a  suffix that indicates support for the 3270 Extended Data Stream.

Default and alternate screen sizes
Models 3, 4 and 5 also implicitly emulate a model 2 as well. This is known as the default screen size. When the host sends an Erase/Write command, it sets the terminal to the default screen size. When it sends an Erase/Write Alternate command, it sets the terminal to the alternate screen size (the size listed in the table above).

Some hosts also allow the screen to be larger than the alternate size. This is configured through the oversize resource.

Examples
Color display, 43 rows, 80 columns, extended data stream: 3279-4-E Monochrome display, 24 rows, 80 columns, no extended data stream: 3278-2