Do not use line mode when the diagram would be too complex to be read by touch.

Where the technology is available, it is often better to represent lines in diagrams with tactile graphics.

Use the horizontal line mode indicator to open any horizontal line.

Within horizontal line mode, use the appropriate horizontal line segments, corners and/or crossings to represent the line.

When an arrow is continuous with the line, use the arrow indicator \ to signal the beginning of the arrow. Use the symbols of arrow mode to represent the arrow. Upon completion of the arrow, horizontal line mode continues. Refer to: Guidelines for Technical Material, Part 13, for rules on constructing arrows.

To represent distinctive types of lines, use any valid single-cell UEB symbol in addition to those indicated in 16.2.2 and excluding the arrow indicator \, the horizontal line mode terminator ' and space. In general, choose a symbol based on the physical shape of the line or feature (such as a junction) rather than the meaning of the symbol in other contexts.

Terminate horizontal line mode with a space or with the horizontal line mode terminator.

When the variant horizontal line segment is used, describe the line it represents on the special symbols page or in a transcriber's note.

Use the diagonal and vertical line segments to represent diagonal and vertical lines. Group one or more of the symbols together when necessary providing that each group is surrounded by spaces.

When a line drawing is in a text in contracted (grade 2) braille and when a string of two or more of the line-drawing characters < and > occur in the line drawing in any combination and surrounded by spaces, use grade 1 mode for the line drawing.