=Concepts=
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! style="background: #efefef;" | Name !! style="background: #efefef;" |Description
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| HistoryManager || Manages a collection of items. 
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| (History) Item || An item of HistoryManager is ''a time-series'' collection of samples; a file or memory array. It's random-accessable, streamable and appendable. 
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| Sample || An entry in history item. It's a record that contains time and value, possibly other fields too.
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| (Sample)Format || The record type description of a sample.
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| Collector || Utility that samples a value from data source and writes to history items according to its configuration.
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| SamplingFormat (class) || Named description how a datasource's item is to be sampled by a collector. Used for Trend's history subscriptions.
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| Datasource || An information system that has variables. Provides values to Collector utility.
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| Variable || A variable in a datasource.
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