Clearly the asterisk is a popular web standard for identifying unconditionally required fields.

But what if any one field out of several is required? For example, there are separate fields for home phone, work phone, and cell phone. At least one phone number of any kind is required.

Do people usually just indicate this using in-page instructions? Instructions aren't very elegant, but it seems like asterisk variations (hatchet, cross, etc) usually just confuse people. Is there a better solution?

4 Answers 4


I'm not aware of a conventional better solution. In situations like these I try to do something like this, with visual grouping of the alternative fields and placing the asterisk next to the group title:

enter image description here

Sometimes it works, sometimes - not so much.

Also, it's always a good idea to use inline validation, but it's doubly helpful here.

  • Yep, this is definitely better than instructions at the top of the page. Thanks for the help.
    – Baa
    Commented Apr 22, 2011 at 5:37
  • This style would be my preferred approach. the asterix ( which is a known indicator ) then is seen to relate to the whole group. Grouping is often a good idea. Commented Aug 9, 2011 at 17:00

Just to illustrate @Rain's answer and LKM commentary, this is a solution I've been using for a long time with great results:

At least one field required

  • +1 - Great solution, though it does look as if it would encourage people to enter just one. Commented May 29, 2011 at 9:33

You may also be able to rephrase the question and avoid the somewhat unusual "at least one is required" construction with something like this:

Phone Number Type Example

It is a little clunky, but it does get around the problem of presenting a user with a form type that most people haven't seen before.

  • This is great, but I also need to allow the user to enter multiple phone numbers. So this approach would involve six fields instead of three. Great idea though, and I can see myself using it for other purposes in the future.
    – Baa
    Commented Apr 22, 2011 at 5:35
  • Great out of the box thinking! Commented Apr 22, 2011 at 7:23
  • 2
    If people have the ability to add more than one entry, add a "+" button below the dropdown/field combo that adds more of 'em, or simply show more than one entry, make the first required, and default the other dropdowns to something like "None" or "Select More".
    – LKM
    Commented Apr 22, 2011 at 14:57
  • @Baa That makes sense, if you want to still leave the option open for many different phone numbers Vitaly's answer is almost certainly the way to go.
    – Rain
    Commented Apr 22, 2011 at 16:07

For examples like the home, office, mobile phone I tend to use Fieldset and Legend HTML tags to group the options together (after all this is what they are intended for). The legend can then say something like 'Provide at least one phone number*' - with the conventional asterisk at the end for easy recognition. The fieldset wraps the inputs for the 3 phone numbers.

This conveys good visual meaning and cues to sighted users and a web standard compliant technique that is accessible to screen readers etc.


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