Every database, group, or document in your DEVONthink database has a URL (uniform resource locator) associated with it. While web URLs typically begin with http:// or https://, DEVONthink's URLs take the form of x-devonthink-item:// followed by a long alphanumeric ID. These are most commonly used for backlinks and deeplinking, even with external applications. But item links can also be used as a type of automation when extended with URL parameters.
You can get this item link manually by selecting a document or group and choosing Edit > Copy Item Link. You then can manually extend the copied URL with the following parameters, as needed:
app: Used in conjunction with the openexternally parameter, specify the name of the app to open the referenced file with, e.g., x-devonthink-item://E35A4AFF-BD90-4131-9D54-62849E0EF4DE?openexternally=1&app=preview.
length: Specify the number of characters from the start parameter. Used in selection links.
openexternally: Opens the referenced item in the system default application, e.g., opening a PDF in Preview. Used with a value of 1, e.g., openexternally=1.
opentab: Opens the referenced item in a new tab in the current main window if a document is already being viewed. Used with a value of 1, e.g., opentab=1
page: Opens a PDF to the specified page. Usage: page=<integer>.
reveal: Reveals an item in the item list instead of opening it in a new window. Usage: reveal=1.
search: Directly jumps to the first occurrence of the search string in the specified document. Usage: search=<string>.
start: Specify the starting character on the current page. Used in selection links.
time: Directly jumps to the specified time in seconds in a video or audio document. Usage: time=<float>.
Terminology
Manually getting item links can be useful for some hard-coded cases, but there are many times you want to get them programmatically. There are two AppleScript properties for a record related to item links:
reference URL: This is the item link as described above.
UUID: This is the unique identifier of the item, i.e., the long alpha-numeric string in the reference URL.
Here is an example of getting and using an item link to create a Markdown compliant link on the clipboard:
The terminology for using item links can depend on the capabilities of the application you're scripting. Here is an example, using a hard-coded URL, with an application that can open URLs:
P.S.: For the shell scripters, the URLs can be used with an open command.