I read the post about hyphens
https://www.EnglishForward.com/English/RulesForUsingHyphens/gqxx/post.htm
I am in the medical field (pathologist) and have been criticized for hyphenating rule-in and rule-out in my diagnoses and comments.
. . IT WOULD BE DIFFICULT TO CONFIDENTLY RULE-IN or RULE-OUT CLINICALLY SIGNIFICANT ENDOMETRIAL LESION . .
I think it follows the ' makes it easier to read' rule
I always see ' rule out ' without a hyphen. I never see 'rule-in', with or without a hyphen.
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I always see 'rule out' without a hyphen.
I never see 'rule-in', with or without a hyphen.
You shouldn't hyphenate those. Phrasal or prepositional verbs are not hyphenated. The hyphenated forms (or closed words) are for the corresponding nouns. If there was something called "a rule-in" or "a rule-out", which I'm not sure there is, then that would be hyphenated.