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Draws horizontal sundials featuring a graphical converter and movable ring (example). Uses millimetres for all lengths. Uses decimal degrees for all angles.

Type of dial required	Civil Time Dial with Daylight Saving Time using North American rules (second Sunday in March; first Sunday in November). Civil Time Dial with Daylight Saving Time using European rules (last Sunday in March; last Sunday in October). Civil Time Dial without Daylight Saving Time adjustment. Hours To Sunset (reverse-numbered Italian dial).
Dial latitude
Longitude offset from timezone meridan	-7.5° to 7.5° only, positive for a location east of the meridian. This setting is ignored for Hours To Sunset dials.
Dial diameter
Gnomon width
Ring widths
Material width	Give dimension for Landscape orientation.
Material height	Give dimension for Landscape orientation.
Calendars' short tick length	Day marks.
Calendars' long tick length	Five day marks.
Hour scale's short tick length	Five minute marks.
Hour scale's medium tick length	Quarter hour marks.
Hour scale's long tick length	Hour marks.
Colour for the edges of the movable ring	Black Red Green Blue Pale Red Pale Green Pale Blue White
Colour for minor divisions on the converter scale	Black Red Green Blue Pale Red Pale Green Pale Blue White
Colour for hour lines	Black Red Green Blue Pale Red Pale Green Pale Blue White
Colour for labelling aids	Black Red Green Blue Pale Red Pale Green Pale Blue White
Line widths
Use double width lines for hour lines and hour marks
Gnomon offset	Using anything but 0 is not recommended in most cases - see notes below.

• No month labels or hour numbers are drawn by the program - you must add them afterwards using CAD or drawing software such as Inkscape.
• The dial is drawn with both calendar scales running anticlockwise. Perhaps the easiest way to figure out which month is which is to locate February - the only month with 29 daily tick marks. Remember that for dials featuring Daylight Saving Time (DST), there are periods of 7 days in the spring and autumn that can fall in either DST or in Standard Time (ST). It is the handling of these periods that leads to extra partial 'months' appearing in the calendar scales. For example, with North American DST rules, March is split into two 'months' : one runs from March 1 to March 14 for ST, the other runs from March 8 to March 31 for DST. Likewise, we have a 'month' for November 1 to November 7 as DST, followed by November 1 to November 30 as ST. To aid understanding, it may help to look at an example.
• For the Hours To Sunset dial only, the hours scale runs anticlockwise (from 0).
• In Landscape orientation, A4 paper is 297mm wide × 210mm high and Letter paper is 279mm wide × is 216mm high, so for a drawing that will fit on either, use a width of 279mm or less and a height of 210mm or less.
• The gnomon footprint is drawn with the minimum length (substyle) needed to ensure its shadow always reaches the dial scale's innermost arc. Of course, a longer gnomon may be used if desired (e.g. aethestic reasons, easier assembly).
• You can deal with time zone offsets outside the allowed range by adding or subtracting multiples of 15° and the adjusting hour label positions accordingly.
• If you want a PDF version of the diagram, either use your operating system's Print To PDF feature, or save it as an SVG file and then use an online conversion service such as www.fileformat.info.
• Labelling aids are extra marks on the dial face that can help with label placement. They are not relevant to dial use, and are intended to be deleted from the drawing once labelling is finished.
• The program cannot handle the 'midnight overlap' that affects dials in polar locations, so these latitudes are not allowed. In practice, due to the effect of atmospheric refraction on sunset times, and also computational limits of the program, the maximum latitude supported is ±65.5° - slightly outside the Polar Circles.
• Although the program allows you specify them, dials for latitudes within about ±30° of the Equator will be unusable in practice. This is due to excessive bunching of lines making up the graphical converter.
• Using a non-zero value for 'Gnomon offset' causes the toe of the gnomon to move away from the centre of the dial, which may reduce bunching of converter lines at the cost of more bunching elsewhere. Positive values move the gnomon up the diagram.
• RGB colour codes used are Black:0,0,0; Red:255,0,0; Green:0,255,0; Blue:0,0,255; Pale Red:255,170,170; Pale Green:170,255,170; Pale Blue:170,170,255; White:255,255,255. Even white lines are present in the diagram; you just don't see them against the white background.
• For an explanation of the workings of these dials see Lelievre, Steve. 2017. "A Horizontal Tide Dial" in The Compendium, Journal of the North American Sundial Society, v.24, no.4. ISSN 1074-3197.. It's not quite the same kind of dial, but it covers the general concept.
• This dial design was inspired by the Sawyer Equant.