REST detail annotation makes an ABL routine (internal procedures, methods, and user-defined functions) available as a REST resource. This annotation must precede the internal procedure or function, or method statements. When you use this annotation, you must also use an REST main annotation at the beginning of the source files.@openapi.openedge.export(type="REST", useReturnValue="{true | false}", writeDataSetBeforeImage="{true | false}").

type
This attribute specifies the type of defined service such as REST for a REST service or DataObject for a DataObject service. This is a mandatory attribute.
useReturnValue
This attribute specifies whether a return string is used for the internal procedures. The default value is false. This is an optional attribute.
writeDataSetBeforeImage
This attribute specifies whether before-image data is written out when ProDataSet parameters are serialized as XML. The default value is false. If no ProDataSer parameters exist, writeDataSetBeforeImage is ignored. Before-image data is not supported for JSON. This is an optional attribute.