How to indicate on a form field that additional important documentation is available?

Question

We have a primarily form-based application. Most field labels are hyperlinked to a formal instructions document via context-sensitive help links (the mouse cursor changes to show this.) This works well to let the user know that information is available if they feel they need it, but in some cases we want to give them the idea that: This is a complicated option that might behave counter to your intuitions. In our documentation, these potential gotchas are often boxed off with an upside-down triangle icon.

How can we best indicate this on or around the form field? Some ideas we've considered, along with concerns:

• a small question mark icon — may feel more like "information is available" rather than "look here even if you're pretty sure you've got it."
• a small yellow upside-down triangle with an exclamation point — may look too much like a warning that there's something wrong with the user's entered data.
• the first several words of the documentation text in small type, expandable by clicking, or other text like "see important information" — may simply add too much clutter to the form.
• Googling for "more info icon" suggests a light bulb, or an ⓘ, or perhaps an i in a cartoon word bubble — the circled i may be an okay compromise in attention-grabbing, between a ? and a warning icon.

Do any of these, or something else, sound like the right thing to you? I've pictured these to the right of the entry field or the label, but perhaps there are better options for that, too. Any examples I can look to for guidance on web pages or existing applications?

Here's an example of this kind of information for our astronomical application domain: Warning: If your object has significant proper motion and the reference target does not have the same proper motion, do not use positional offsets to specify your object.

Answer 1

Using different icons could be an option (like the suggested light bulb in grey vs. the same in red to make it stand out, or even a different icon like a triangle with exclamation mark). It's easy to get this wrong or confusing (unclear what icons mean, color blindness).

You're saying it's in some cases that it's probably not intuitive. If it's a long form adding more icons and always visible, distracting text is probably not the best option.

How about displaying the information only if the corresponding field has focus? One option to display this, just an example:

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