OpenEndpoints will combine all values submitted into a single input-from-request parameter, separated by a multiple-value-separator. The default separator is a double pipe ||.
The above example would result in a parameter "topping" that has the following value:
Some HTML form controls allow to submit multiple values for a single control, for example:
<selectname="topping"multiple="true">
<optionvalue="bacon">Bacon</option>
<optionvalue="cheese">Cheese</option>
<optionvalue="onion">Onion</option>
</select>
On selecting multiple values, this would be submitted by the user agent in the same way as having multiple controls with the same name attribute. The result will be the same as above in OpenEndpoints: