Tick Marks

[Chris Clemens]

We are trying to fully understand the application of tick marks on various graphics. When are tick marks 1/2 inch long and when are tick marks 1/4 inch long on graphics involving axis lines? Or should tick marks always be 1/2 inch long whether they are on one side or both sides of axis lines?
In general, tick marks for numbers lines and graphs are stated in the tactile guidelines as being 1/2 inch long with 1/4 inch on EACH side of axis lines [3.4.3.4]. In the general rules for gridded graphs [6.6.1.2], the guidelines state that tick marks should be 1/2 inch long with 1/4 inch on EITHER side of the line.
In the subsection for Cartesian Graphs [6.6.2.2] and the section for Line Graphs [6.6.4.4], the guidelines state that tick marks should cross or straddle “the axis lines, 1/4 inch (6 millimeters) on EITHER side of the axis lines.” Because of guideline 3.4.3.4, it seems we are to infer that the tick marks are 1/2 inch long although in these situations it is not specifically stated.
The examples on pages 6-40 and 6-41 show the tick marks only on one side and not straddling the axis lines. The examples of tick marks on bar graphs (pages 6-44) also show tick marks on only one side. NONE of these examples appear to show 1/2 inch long tick marks.

[dspence]

Dear Georgia Braille,

As you state in your question, Section 3.4.3.4 states, "Locational (Secondary) Lines...tick marks on number lines and graphs...must be 1/2 inch total...1/4 inch on each side of line... For clocks, the tick marks should straddle the circumference line and extend no less than 3/16 inch and no more than 1/4 inch on either side of the circumference." Our feeling was that 1/2 inch for clock was too long. The tick marks on clocks can range from 6/16 inches to 1/2 inches on the circumference line. The smaller the clock face the shorter the tick mark.

6.6.2.2 3rd bullet, "Tick marks on the horizontal and vertical axis lines...should cross the axis lines, 1/4 inch on either side of the axis line." This was meant to imply a total of 1/2 inch for the tick marks on the lines of a Cartesian Graph. Example 10 in the TG Supplement shows where tick marks on a Cartesian Coordinate graph do extend on both sides of the X and Y axis lines.

The examples shown on 6-40 and 6-41 are the braille examples...meaning that the TG Guidelines do NOT show the print. These braille examples were meant to show the alignment and placement of the labels in relation to the vertical grid line. They were not meant to be interpreted as "tick marks." These short lines on one side of the x and y-axis lines are not tick marks, they are vertical grid lines (an extention of the grid lines).

In response to your last comment about none of the examples showing the the vertical grid lines being 1/2 inch...these examples are reduced in size in order to fit on the print page. In actuality...these vertical grid lines should be 1/4 inches.

Hope this helps, if you have more questions, let me know! Diane

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