BACKGROUND 
There are many systems currently 
marketed that handle geographic data. 
They have existed long enough to generate 
databases of significant sizes. It follows 
that the usefulness of being able to accept 
data from existing database and distribute 
data to other systems is well recognized. 
With the practice of data exchange has 
come frustration. Most of those who have 
tried to accept data from an outside source 
have found that the process usually takes 
much longer than planned. Also, the 
converted data requires a significant 
amount of additional processing before it 
can be integrated into the target system. 
This paper argues that the problem of 
information transfer is being addressed at 
the wrong level and, that this is the 
primary reason for limited success with the 
process. What is required is the ability to 
convert application models; what is 
provided is data translation. 
To support this argument, the modelling 
process is examined from the application 
level through to the data format level. 
Data translation and data standards are 
discussed in light of the modelling process 
and a set of specifications for information 
exchange is presented. 
APPLICATION MODELLING 
An application starts with a real world 
process. To use the computer in the 
analysis of that process, a model must be 
created. From the application, application 
entities must be extracted and appropriate 
GIS constructs assigned. Each GIS 
construct has data models and each data 
model has many different formats that can 
be used to represent it. 
Application Entities 
i 
GIS Constructs 
i 
GIS Models 
i 
Data Formats 
including 
Points/Lines 
Matrices 
Non-graphic Attributes 
Interrelationships