Each linetype is defined on two lines in a linetype definition file. The first line
contains the linetype name and an optional description. The second line is the code
that defines the actual linetype pattern.

The second line must begin with the letter A (alignment), followed by a list of pattern
descriptors that define pen-up lengths (spaces), pen-down lengths (dashes), and dots.
You can include comments in a LIN file by beginning the line with a semicolon (;).

Linetype Definition Format

The format of the linetype definition is

*linetype_name,description 
A,descriptor1,descriptor2, ...

For example, a linetype called DASHDOT is defined as

*DASHDOT,Dash dot __ . __ . __ . __ . __ . __ . __ . __ 
A,.5,-.25,0,-.25

The example indicates a repeating pattern starting with a dash 0.5 drawing units long,
a space 0.25 drawing units long, a dot, and another space 0.25 drawing units long.
This pattern continues for the length of the line, ending with a dash 0.5 drawing
units long. The linetype would be displayed as shown below.

__ . __ . __ . __ . __ . __ . __ . __

LIN files must be saved in the ASCII format and use a .lin file extension.

Linetype Name

The linetype name field must begin with an asterisk (*) and should provide a unique,
descriptive name for the linetype.

Description

The description of the linetype should help you visualize the linetype when you edit
the LIN file. The description is also displayed in the Linetype Manager and in the
Load or Reload Linetypes dialog box.

The description is optional and can include

• A simple representation of the linetype pattern using ASCII text
• An expanded description of the linetype
• A comment such as “Use this linetype for hidden lines”

If you omit the description, do not insert a comma after the linetype name. A description
cannot exceed 47 characters.

Alignment Field (A)

The alignment field specifies the action for pattern alignment at the ends of individual
lines, circles, and arcs. The program supports only A-type alignment, which guarantees
that the endpoints of lines and arcs start and stop with a dash. You must specify
A-type alignment by entering A in the alignment field.

For example, suppose you create a linetype called CENTRAL that displays the repeating
dash-dot sequence commonly used as a centerline. The program adjusts the dash-dot
sequence on an individual line so that dashes and line endpoints coincide. The pattern
fits the line so that at least half of the first dash begins and ends the line. If
necessary, the first and last dashes are lengthened. If a line is too short to hold
even one dash-dot sequence, a continuous line between the endpoints is drawn. For
arcs, the pattern is adjusted so that dashes are drawn at the endpoints. For circles
and other objects without endpoints, the dash-dot sequence is adjusted to provide
a reasonable display.

Pattern Descriptors

Each pattern descriptor field specifies the length of segments making up the linetype,
separated by commas (no spaces are allowed):

• A positive decimal number denotes a pen-down (dash) segment of that length.
• A negative decimal number denotes a pen-up (space) segment of that length.
• A dash length of 0 draws a dot.

You can enter up to 12 dash-length specifications per linetype, provided they fit
on one 80-character line in the LIN file. You need to include only one complete repetition
of the linetype pattern defined by pattern descriptors. When the linetype is drawn,
the application uses the first pattern descriptor for the starting and ending dashes.
Between the starting and ending dashes, the pattern dash specifications are drawn
sequentially, beginning with the second dash specification and restarting the pattern
with the first dash specification when required.

A-type alignment requires that the first dash length be 0 or greater (a pen-down segment).
The second dash length should be less than 0 if you need a pen-up segment and more
than 0 if you are creating a continuous linetype. You must have at least two dash
specifications for A-type alignment.