This question brings up an important question:

Do we want to allow or avoid the use of non-standard English such as the words zie and zir as non gender specific pronouns on this site?


Question: What is the best way to indicate when fields are empty in read-only mode?
Answer: It depends...

One of the biggest challenges with "data intensive" is making sure the information is displayed is meaningful to what the user is trying to accomplish at that step.

So first, make sure you have the right information - and the right non-information, ie: the information NOT shown at this step also makes sense and it's expected to NOT be there. (Make sense?)

To answer your question using the simplified example you've shown above, you could do one of the following, but again, only if it makes sense given the task scenario:


Display nothing. But only if nothing actually means something that is mutually understood by all users.
Say nothing. Show some text that tells the user the input field was left blank, like literally: "None" or "Intentionally left blank" - but again, only if the words don't imply something they shouldn't be implying.
Use a visual cue. If this occurs often, you might want to use the same graphic to indicate the same situation - like an input box that's grayed out - so that the user knows it's possibly something to edit/modify versus a data point being automatically displayed or pulled in from elsewhere.


That's all I think of off the top of my head for now. Again, all of this is contingent on what the actual information is and how the user expects to interact with it, behaviorally or cognitively. 

P.S. For checkboxes, you can use Enabled/Disabled or On/Off - but again, I can't stress this enough because of how often these controls are used inappropriately - it depends on what it represents to the end user.