For our app, we looked at creating a guideline on what to display when data is (temporarily) not available. The scenario: it's a technical application, a service engineer clicks a piece of equipment and the UI shows details about it in a side bar (name/value pairs). Some fields might be not available for technical reasons, say a communication layer/bus is not working, the software is not providing it yet, etc. We looked at several options, like not showing a value at all (i.e. an empty value), showing a '-', a '?', 'N/A', 'n/a' etc. Examples:

Physical Address Serial Number Status
3434.435.23 ? N/A

We wanted to settle on 'N/A', as an empty value, ? or - do not communicate intent (see also here).

Still, we identified that for most people there is a distinction between:

  • Not Applicable - Value is not relevant for this piece of equipment (and will never be)
  • Not Available - Value is relevant, but just not available right this time

and N/A can be translated as both (one could argue how important this distinction is for the user of course). We also got this feedback when presenting it. Any other ideas or guidelines on this?

  • 1
    "Status: N/A" can also give the impression that the equipment is unavailable.
    – jazZRo
    Commented Nov 16, 2023 at 13:49

1 Answer 1


For clarity, be straightforward and use actual words: put “Unknown” in the field when the data is not available.

To emphasize that this is meta-information about the display, and not an actual data value, and to make the table easy to scan, give it a different style, possibly de-emphasized (e.g. slightly gray, or italic).

If further clarification of the exact situation may be useful, then add a pop-up to explain what the value means with an entire sentence, such as “The device is not responding; this information has not been successfully retrieved.” Or, if applicable, you could make the text a link to an error log for the unsuccessful retrieval attempt, or similar diagnostic information or tools.

  • I actually made some design proposals, and Unknown in slightly gray was one of them! When presented to a target audience, it was not met with great enthusiasm, mainly because the general feel was that 'Unknown' is like '?' or '-': it does little to express the meaning, while people felt 'not available' was much better at that. Now we are having the Not Available vs Not Applicable discussion, maybe we should reconsider.
    – Stiggy
    Commented Nov 16, 2023 at 9:47
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    @Stiggy In my experience, it's very unlikely you’ll find exactly the right single symbol or word, that everyone agrees is clear. That's why I suggest backing it up with a popup or link, so that if any user experiences uncertainty they can get it cleared up.
    – Kevin Reid
    Commented Nov 16, 2023 at 15:50
  • Thanks for your insights @Kevin Reid! Got little other ideas or inspiration, so I think I will go with “Unkown” or “Not avail.”, in a slightly different style and a tooltip.
    – Stiggy
    Commented Nov 18, 2023 at 9:18

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