This enumeration allegedly specifies the units of measurement for a string. But as all the string measurement functions actually use the (remarkably similar!) GraphicsUnit enumeration instead, we will pretend that we never saw it, and move along quietly . . . .

public enum StringUnit {
   World = 0,
   Display = 1,
   Pixel = 2,
   Point = 3,
   Inch = 4,
   Document = 5,
   Millimeter = 6,
   Em = 32
}

Hierarchy

System.Object System.ValueType System.Enum(System.IComparabl, System.IFormattable, System.IConvertible) StringUnit