Is there a rule on when under and over are used as prefixes rather than adverbs when attached to past participles (and whether or not they are hyphenated)?
In general, it seems that both words are sufficient as adverbs, e.g., "this paper is under cited." However, we often see under and over attached as a prefix, e.g., "this paper is under-cited." In addition there are certain words where under/over are "built-in", e.g., "this company is understaffed." Is this simply a matter of convention or are there clearer rules on how the words should be paired? Are there differences in meaning when under is used as an adverb rather than a prefix (e.g., does "under cited" mean something different than "under-cited")?