REST docs don't make it clear how to set a value in a select list custom field

I eventually figured out that I need to send this:

"customfield_10112":

but this wasn't obvious. The docs at http://docs.atlassian.com/jira/REST/latest/#id161551 certainly don't have any custom fields that look like this.

Please add an example along these lines (with a comment explaining it) to the docs.