Drop-downs are used to restrict user's entry in a form field to a list of available values. These can be multi-select using
<span class="danger">(hyperlink to the multi-select)</span>.
<br/>If there are 6 or fewer options, use a button-group instead of a drop-down. See <span class="text-danger">(cross-reference button topic)</span>.
<br/>Check out <a href="https://angular-ui.github.io/bootstrap/#/dropdown" target="_blank">UI-Bootstrap's
    documentation</a>