related-article-type should have one of the following values: "addendum", "commentary-article", "companion", "series", "retracted-article", "corrected-article", "concerning-article", "translated-article", "republished-article", "response-to", or "publisher-note"
This rule ASSERTS the following, raising an alert if FALSE:
@related-article-type = ('addendum', 'commentary-article', 'companion', 'series',
'retracted-article', 'corrected-article', 'concerning-article', 'translated-article',
'republished-article', 'response-to', 'publisher-note')