Using a color two shades deeper than the base provides depth and definition.
Another common definition uses a human body, standing upright, as a frame of reference.
In other literature, you should take care to find out which definitions the author is using.
There the definition uses derived categories, and looks very different.
The following definitions use the notations shown in the figure.
The definition uses the idea, explained on its own page, of a central series for a group.
The above definitions are no longer the most commonly used in either system of units.
Note that the previous definition uses a vertical circular cross section.
The definition should use terms other than person to describe what a person is.
Other definitions use 15th Street on the north and 24th Street to the south.