Each generation away from original survey work introduces more error no std. Symbolization Method how to show quantities on map graduated symbols, color coding, etc. Reduction Methods Compiler lifts or traces selected info. Sometimes our source materials have limitations or are incomplete . They may present special problems of presentation because of technical terminology or because of the quantities of detail required to make a point .
Some data needs to be qualified .
These limitations must be considered from the very start of a project so that they can be addressed in the design of the map.