Create Line Patterns

Line patterns are added to the master file, referenced by environment variable uslXmaster. This section describes how to create a line pattern definition.

A line pattern definition has the following format:

• begin_pattern patterns the beginning of the line segment

• repeat_pattern patterns the remainder of the line segment. These two parts make up a full pattern.

• short_pattern is used only when a line segment is shorter than a full pattern.

A pattern consists of one or more line patterning commands and may include qualifiers.

The first and last pattern of the line segment are usually mirror images. The begin pattern usually matches the last pattern command in the repeating pattern definition.

Blanks and dashes in a short pattern must be normalized. The short pattern is repeated in a short segment as many times as the length of the segment allows.

A pattern should start with a blank or dash command to ensure that proper rotations are performed. Starting with a symbol or arc results in an undefined angle for the line segment, and the corresponding symbol or arc is rotated 0 degrees.

If a significant point is encountered and a new pattern started, it begins at the first blank or dash command in the pattern.

Half dashes and blanks at significant points

Half dashes and half spaces are automatically outputted at significant points on a line. For example, dashed lines that are open (i.e. do not form a closed loop) begin and end with a full dash. Dashed lines which form a closed loop begin and end with a half dash, which looks like a full dash spanning the end points of the line; other significant points in the closed loop require a half dash or blank to span them.

First blank or dash specification is used in the begin_pattern to symbolize a half dash or space at the start of a line. A line which must begin with a half dash or space is symbolized starting at that point in the begin segment. This is another good reason to always begin patterns with a dash or blank command. If there is no begin_pattern, then the lead half dash or space function is disabled. CARIS uses the very last blank or dash specification in the current pattern to output a half dash or space at the end of a line.