I have a form where fields are marked (*) to indicated they are required. But there is a strange use case where Level and Space have a dependency on each other such that either space or level or both space and level are required:

enter image description here

Obviously the sensible option would be to combine level and space into a single 'location' option, but due to time constraints the developer cannot. So we're stuck with this awkward situation where we have to make it clear on the interface either or both space and level are required.

question: how do I indicate to the user that at LEAST one of these fields is required?

3 Answers 3


To answer your specific question " is there an established pattern for this kind of thing?", the the answer is YES, THERE IS.


Best practice for indicating required fields

Guess what: users don't care about required field indicators very much either. OK, we admit that a few of us webby-geeky types know what they are, and may even inspect the form before filling it in to assess the intrusiveness and amount of effort. But most everyday people don't really know what those little asterisks are for, even if they notice them at all.

So do this:

  • choose an indicator, preferably a red asterisk
  • explain what it is, in plain language and at the start of the form fields
  • put the indicator in a consistent place relative to the labels
  • decide on a way to tell someone using a screen reader that the field is required
  • if you decide to indicate optional fields instead, use the word 'optional'. Do not use a red asterisk to indicate 'optional'.

* Is this a required field?

enter image description here enter image description here

this is why you used that: because it's a common and accepted pattern for required fields. Please note that the article immediately above these lines with the screen captures is for 2010, so you can see how it was accepted as a common UX approach 5 years ago and older.


...I'm not saying it's the best approach. There are some approaches that might work better for you, for example:

Back to iOS

If you want more help on th technical side of implementation of iOS, take a look to Simple Form Validation for iOS

  • 1
    The OP is asking about a specific case where either Field A OR Field B is required, but not necessarily both as oppose to general best practice for indicating required fields.
    – nightning
    Sep 21, 2015 at 21:41
  • nice answer, but my question was specific about validating a group
    – colmcq
    Sep 22, 2015 at 9:13

Marking a group title with an asterisk can be pretty confusing.

How about writing in plain English? Something like "You must provide your phone or email address".

Also, if you don't want users to provide both, you can combine those fields into a single field and call it "Phone or Email". And you'll be able to put asterisk on that label.

  • This simply lacks the simple intuition if modern mobile devices. Plain English will communicate a message slower then, say, a symbol, color, or group, etc. I believe that with this new era of tech, we should focus on communication without the sole reliability on language. You're software, to some extent, should be useful to people who speak a different language then the program supports, and hence we should aim for this implied intuition, as it is what drives digital experiences to be intuitive, easy, and fun.
    – DripDrop
    Sep 24, 2015 at 3:11

First Approach

I think that you should make the text of required fields red, either #F00 or similar brightness, and clearly indicate what that means beforehand.

This approach is more noticeable, and harder to miss than the classic "red asterisk" approach, but is still reminiscent of it.

Another thing to keep in mind is when to let your users know a field is required. Maybe you only want users to know a field is required after they have entered it empty once. In this case, wait for a "required" field to be entered in empty, then pop the input window up again, clearly saying that the field did not have sufficient data.

Second Approach

Or, if you are feeling like an even more intuitive approach, you may find success in grouping together important and less/not important fields. For example, let's say you want the user to enter:

  1. Their username.
  2. Their password.
  3. Their real name.

But only the first two were important enough to be required. In this case, maybe have the users enter the required data first, and then, in a separate step, then go on to enter less important information, but this time with a simple "skip" button.


To summarize:

  • Use red text:
    • Possibly wait for a "failed" attempt beforehand.
  • Use multiple steps/groups:
    • May remove the tedium of the "red asterisk" or "red text" approach.
  • I'm not really sure how this is going to help in this particular case. But thanks for taking the time to reply.appreciated
    – colmcq
    Sep 24, 2015 at 8:40

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