Out of the box, RT supports many custom field types. Beyond the simple "type in a value" and "select a value from this list", RT's custom fields can be images, wikitext, multiple attachments, and more. This variety in custom field types goes a long way towards helping organizations achieve the exact workflow they need.
In RT 4.0, we add two new types to this list: Date/DateTime and IP Address custom fields. We also add new display types for select-value custom fields: dropdown, radio list, and checklist.
Date and DateTime custom fields
RT has several DateTime fields built into its core, including Due, Starts, Resolved, etc.
When you edit such DateTime fields, RT pops up a calendar and a time selector so you can quickly click a date and time instead of typing them. But if you do type in a value, we're smart about parsing people-friendly date formats. Type in "next Monday" and we'll convert that into RT's timestamp format for you. RT's search engine also has logic for dates so that you can search for them in a natural way. If you use the search builder to construct a Resolved = '2011-03-21' (or Resolved = 'yesterday') clause, we rewrite that internally to (Resolved >= '2011-03-21 00:00:00' AND Resolved <= '2011-03-21 23:59:59') since that's the logic you want. Finally, users can configure the format that RT displays DateTime fields to them. While I personally like 2011-03-21 20:00:35, someone else may want Mon, 21 Mar 2011 20:00:35 GMT.
In RT 4.0, your business-specific custom fields can enjoy these features too! For example, you can use a DateTime custom field to track when your customer's package left your warehouse, then later search for tickets within a particular shipment window. Many sites are using the "type in a value" custom field type for dates. When you upgrade to RT 4.0, you'll be able to upgrade those custom fields to get better (and consistent) searching, entry, and display. When someone types "next Monday" into a DateTime custom field, you'll actually be able to find that ticket again.
RT 4.0 also adds date-only custom fields, for when you don't need to-the-second granularity. You still get all the benefits of a consistent format, user-specific display preferences, and intelligent searching and input.
IP Address custom fields
RT for Incident Response, our computer security response system built on RT, has had support for IP address custom fields since its inception. We want to share that bit of RTIR with the greater RT community, so we've factored IP address custom fields into the core.
RT's IP address custom fields include support for IPv4 and IPv6, as well as IP address ranges (in CIDR format or simply 192.168.1.0-192.168.1.255). You can search for tickets with IP addresses in a particular range, using either the CIDR format or the regular range format.
We also validate what you type into IP address custom fields are actually possible IP addresses.
RT has always used a listbox widget for editing select-one and select-many custom fields. With RT 4.0, we've added an oft-requested feature: dropdown and radio lists for select-one custom fields, and checkboxes for select-many custom fields.
Dropdown custom fields are compact and are consistent with the rest of the select-one fields in RT. Dropdowns also have great support from many mobile web browsers.
Radio lists let you see every option at once. It takes only a single click to select a value.
Whether you use a dropdown or radio button list is up to you; it probably depends on how many values the custom field can have. If there are a lot of values, a radio list is unwieldy.
Select many custom fields also have a new display type: checkboxes.