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By convention, an AIDA data provider that supports setting values will accept either a single scalar or vector value, or a list of named scalar or vector values. The EPICS channel access data provider is of the former sort, and the SLC Magnet server is of the latter.
NB: Presently, only the EPICS Channel Access data provider supports this tool. This is because it's the only data provider that knows how to convert the string you provide on the command-line into a value of the type appropriate for the underlying system.
An example of setting a scalar EPICS process variable:
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