I don't know if the property (which property?) has been set. What I know is that "Company Home > Pending Publication > Submissions" space has a content rule that adds the custom aspect "Reviewers" added to incoming documents. I can open up the Details page on the documents and add values for the 3 properties of the Reviewers aspect, Reviewer1, Reviewer2 and Reviewer3. This aspect and its property values persist when the document is copied or moved into other spaces.
I have defined a content rule for the "Company Home > Pending Publication > Submissions > In Progress > Under Review" space that is applied to incoming documents that have the Reviewers aspect. This rule executes a JavaScript file. However, when I copy a document which has the "Reviewers" aspect and has had values entered for the Reviewer1, Reviewer2 and Reviewer3 properties into the "Under Review" space, in this JavaScript code even though document.hasAspect("custom.Reviewers") returns true, document.properties["custom:Reviewers"] returns null and document.aspects["custom:Reviewers"] is undefined.
If I need to set the property, how do I do it? The Node Browser has been of no help. Its results are pretty much meaningless to me.