At the start of a project, you load the linetypes that are required for the project so that they are available when you need them. If you want to know what linetypes are already available, you can display a list of linetypes that are loaded in the drawing or stored in an LIN (linetype definition) file.
AutoCAD LT includes three linetype definition files: aclt.lin, acltiso.lin, and ltypeshp.lin. Which linetype file is appropriate depends on whether you use English or metric measurements.
The linetype definition file ltypeshp.lin contains several complex linetypes.
If you select a linetype whose name begins with ACAD_ISO, you can use the ISO pen width option when you plot.