There can be between 3 and 6 author keywords.
These are the keywords that an author manually enters for their article. Therefore it is not a controlled list and often the text needs changing to style. Also, required formatting will not always have been applied by the submission process (eg Italics):
There can be between 3 and 6 author keywords. These are the keywords that an author manually enters for their article. Therefore it is not a controlled list and often the text needs changing to style. Also, required formatting will not always have been applied by the submission process (eg Italics):