Basic for information systems (IS) the processing not the information, and organized information or information models is. In IS are stored and processed the information models.
The information model has structure and parts.. It can be organized logically and is realized physically. The logic defines the theoretical description. Physical organization - realization on the computer or carriers as machine words or blocks. The logic description gives the basis to allocate logic units.
Logic unit IS - information object, which has property of indivisibility in aspect of structure and property synergetical in aspect of set of its parts. As against it information unit is connected to indivisibility of the description or different degree of completeness of the description .
In IS the basic procedures are: processing, storage, representation, transfer of the information. It determines appropriate logic units for such processes and systems.
For example, logic unit of a storage in relational Database is the record, and logic unit of processing - transaction. Logic unit of processing in IS is the information model, constructed under the decision of a concrete task
Logic units of representation in the computer diagram are the graphic elements. In GIS  logic units of representation are dot, linear and areal of model. In systems of processing of the images logic units of processing are vectoral and rasterfl of model. In systems of transfer of the information logic units of transfer are: a symbol, word, offer, phras .
Use of logic units enables to carry out comparison and analysis between different areas of researches. They allow to create interfaces for information interchange between information systems and technologies.
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