AutoCAD® linetypes are defined by linetype definition files. These files have a .LIN extension. AutoCAD®'s standard linetype definition files are ACAD.LIN and ACADISO.LIN.Simple linetypes are composed of dots, dashes and spaces. Linetypes containing embedded shapes and text objects are called complex linetypes. Each linetype in a .LIN file is defined on two lines:
*LINETYPE_NAME[, DESCRIPTION]
alignment, patterndescription1, patterndescription2[, ...]
LINETYPE_NAME should be replaced by a significant linetype name. It's not necessary, but you should use the DESCRIPTION-part, to insert a listed name and a kind of line preview.
The alignment field specifies the action for pattern alignment at the ends of individual lines, circles and arcs. Currently, AutoCAD® only supports one alignment action. AutoCAD® rejects any other character(s) in the alignment field.
The alignment field always is A !
patterndescription(n) specifies the length of a line segment. It's possible to enter up to 12 dash-length specifications per linetype. The descriptions may not be longer than 80 characters a line!
Positive values are lines,
negative values are spaces,
lines using length 0 are used for drawing dots!
Let's end with an example:*DASHDOT, __ . __ . __ . __ . __
A, 1,-.5,0,-.5
draws the simple line:
A is always the same1 ... draws a line of 1 DU length
-.5 ... denotes a pen-up (blank) segment
0 ... draws a dot
-.5 ... is another blank, then start from the beginning