The relation attribute @ONNOVALUEis used to define an error if no value can be selected from a Telitab data set.

Syntax

Place @ONNOVALUE:ParameterName,MessageCaption[,Action] in the data slot of the relation

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• This attribute can be for instance be placed in a relation that uses the PARSE#() function to parse external data. The moment some of the data is missing, an error message can be raised.
• This attribute can also be placed in the GET$() function to catch the error when an external process stops without providing output (which you expected to receive). When you do not expect to receive the output, use @OUTPUTNONE in that case Quaestor will not wait for the process and simply continue. However, realise that the latter is not an error catcher while the above can be used as such. 

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