Are you referring to false easting? If measuring in linear distance (meters, feet) this can have the effect of making coordinate values smaller, giving a little more precision and making arithmetic a little easier. Our organization implements a Lambert Conformal Conic projection that subtracts 1,000,000 meters from values for UTM meters.
NAD_1983_Lambert_Conformal_Conic
Authority: Custom
Projection: Lambert_Conformal_Conic
False_Easting: 1000000.0
False_Northing: 1000000.0
Central_Meridian: -100.0
Standard_Parallel_1: 34.91666666666666
Standard_Parallel_2: 27.41666666666667
Latitude_Of_Origin: 31.16666666666667
Linear Unit: Meter (1.0)
Geographic Coordinate System: GCS_North_American_1983
Angular Unit: Degree (0.0174532925199433)
Prime Meridian: Greenwich (0.0)
Datum: D_North_American_1983
Spheroid: GRS_1980
Semimajor Axis: 6378137.0
Semiminor Axis: 6356752.314140356
Inverse Flattening: 298.257222101
This same method is implemented in the state plan coordinate system, for example
NAD_1983_StatePlane_Texas_South_Central_FIPS_4204_Feet
WKID: 2278 Authority: EPSG
Projection: Lambert_Conformal_Conic
False_Easting: 1968500.0
False_Northing: 13123333.33333333
Central_Meridian: -99.0
Standard_Parallel_1: 28.38333333333333
Standard_Parallel_2: 30.28333333333334
Latitude_Of_Origin: 27.83333333333333
Linear Unit: Foot_US (0.3048006096012192)
Geographic Coordinate System: GCS_North_American_1983
Angular Unit: Degree (0.0174532925199433)
Prime Meridian: Greenwich (0.0)
Datum: D_North_American_1983
Spheroid: GRS_1980
Semimajor Axis: 6378137.0
Semiminor Axis: 6356752.314140356
Inverse Flattening: 298.257222101
The two examples given here are useful for Central Texas (the Lambert CC projection given above is in wide use here)--although lately, the WGS Auxiliary Sphere projection is coming into more use as we move towards more work with interactive maps!