and the application data base. For example, if a point 
identifier is updated in the global data base after the 
loading of the application data base, the two data bases 
are inconsistent, and the application software does not use 
up-to-date information. A general solution would be to 
integrate the application program functionally with the 
organisational environment. Complexity of the system would 
be increased tremendously, however. It would be almost 
impossible to design such an application program to be 
portable. 
The front/back-end modules have to be tailored for each 
organisation. This is an disadvantage. However, the clarity 
of the solution is considered to pay off this extra work. 
6.1.2 Implementation of the application (run-time) data 
base 
What kind of technique and tools should we use in 
implementing the application data base when a high priority 
is given for the portability? Especially, should we use 
ready-made, commercial data base systems, or should we 
Program the application data base starting from scratch? 
For the decision, we have to analyse the common properties 
of the commercial data base systems and the needs of the 
application. 
Flexibility: The commercially distributed systems are 
flexible. They have been designed to be adaptable to a wide 
range of applications. On the other hand, they are often 
massive pieces of software. In addition, distribution is 
limited by the licensing mechanism. 
Needs of the application program: Needs, concerning the 
data base, are static. The data types and the access 
methods required will only be changed when the program is 
modified by programming effort. According to the experience 
of the author, only few access types are required. Thus, 
from the technical point of view, there is no urgent need 
for using commercial data base systems. Taking the 
licensing costs, it becomes even more obvious that 
commercial data base systems are usually not the best 
solution. 
What kind of programming style is suitable for hard-coded 
implementations? One possibility is to use data arrays or 
variables to store the information. This is no solution if 
one does not structure the data such that the data base can 
be distinguished from the rest of the program. In other 
words, for the sake of program clarity, it is mandatory to 
structure the program and separate different logical 
components. Data base is one of the concepts that can be 
used in this work. 
As stated earlier, for a data base we have to define the 
data entities and access methods. Those can be implemented 
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