Graduated symbol layers are object themes that use symbols to represent different values. You can use graduated symbols regardless of the type of map object with which you are working. Graduated symbols maps work best when you use numeric data.
Symbols can be displayed for positve and negative values. You can also specify the scale of the view at which a symbol is rendered. This means the symbol will be scaled up or down depending on the scale of the view relative to the reference scale on the Graduated Symbol layer. SymbolBaseSize is available both in the Graduated Symbol layer in the Repository as a Named Layer and also available in the GraduatedSymbolLayer overlay used on the Mapping Service’s RenderNamedMapWithOverlay and RenderMap methods.