Everyone knows how difficult it is to express their own computer needs to others, we will now discover the approach and the tool to use to express our data needs in a clear and rigorous way (without any ambiguity !)  and understandable by everyone.

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We will use the hierarchical approach as a reasoning tool, in other words, we will subdivide a set into sub-sets level by level to arrive at the element (elementary item). Remember (reduce an important problem  to a series of restricted problems) and we will use as a expression tool  of our reasoning, the hierarchical diagram.

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When we consider the organization of the data of a requested output, there are three steps to perform:

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1 °) Establish the hierarchical diagram which gives the organized exhaustive list and ordered of all the elementary data of this Ouput Requested.

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2 °) Define the location of the data on the output media of the system (Status or screen model Etc ...)

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3 °) The table relating external calculations, conditions and data (External Movements) required.

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Of course this may seem obvious, everyone does, but it's so much better to say, let's not forget that we are in a pure logic (we are not here to tweak !)

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Lets' go !

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1 °) The hierarchical diagram.

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The subdivision of the data set of an output is performed using the following subdivision criterion: