How does ArcPad interpret the contents of projection (.PRJ) files?

Answer

Note:
ArcPad was retired as of January 1, 2022. As a retired product, there is no new development, patches/bug fixes, or live technical support. Esri has a suite of apps for mobile GIS and field operations. Depending on your use cases and workflows for mobile GIS and field data collection, we suggest that you investigate the capabilities offered by Esri's other mobile apps.

ArcPad stores an internal list of methods and parameters used for transforming coordinates between two datums. When more than one transformation method or set of parameters exists for two datums, ArcPad, by default, uses the first match it finds in this list. The default transformation method ArcPad uses can be overridden by modifying the file defaulttransforms.dbf in ArcPad's System folder.

ArcPad uses .PRJ files to interpret the spatial projection for shapefiles and other data formats. ArcPad examines the contents of .PRJ files and attempts to match values with internal projection tables. If any values are unmatched, the projection may not work correctly in ArcPad.

Consider the contents of the following .PRJ file:

PROJCS["AGD_1966_AMG_Zone_55",
GEOGCS["GCS_Australian_1966",
DATUM["D_Australian_1966",
SPHEROID["Australian",6378160,298.25]],
PRIMEM["Greenwich",0],
UNIT["Degree",0.0174532925199433]],
PROJECTION["Transverse_Mercator"],
PARAMETER["False_Easting",500000],
PARAMETER["False_Northing",10000000],
PARAMETER["Central_Meridian",147],
PARAMETER["Scale_Factor",0.9996],
PARAMETER["Latitude_of_Origin",0.0],
UNIT["Meter",1.0]]

ArcPad interprets this .PRJ as shown in the following illustration: