I know that italics are required when ortho, meta, and para are included as part of a chemical name (e.g. para-methoxyphenol). However, I'm confused as to whether or not they should be in italics when used outside of chemical names. In discussing structural affects, I might refer to a "para substituted aniline", or a "para carboxy group", or a "methyl group in the para position", or say that the "cis isomer reacts at a faster rate than the trans isomer." I own the ACS style guide (3rd ed), but I can't seem to find a good answer to these situations that are not technically part of a chemical name. Are you always supposed to put these terms in italics and use a hyphen? I also quickly perused some literature, but I can't seem to find a good rule to follow.