Pixels per year
This represents the resolution of the Graph. It is best to strive for a happy medium here. The higher the resolution the larger the graph and more memory will be required. The smaller resolution will require less scrolling, but if glyphs get too close together you will need to increase this. The Glyph Separation value will keep the glyphs from colliding, but too small will make the graph difficult to read. The default is set to 50 pixels / year.
There is one instance where the values are increased in the Time Lord Themes; when studying annual divisions. These changes typically last only a few days, so 50 pixels per year would only be 1 pixel / week. This value is saved along with your Time Lord Themes on the Themes Tab so that you draw your Time Lord grouping with the appropriate resolution.