When a Mult-line Text parameter is selected in the parameters list, the following user interface is displayed:

The Default text entry field lets you choose an initial string of text to be used by the parameter when the plug-in is first applied. Contrary to the simpler Text Field parameter, the Multi-line text parameter accepts text which spans multiple lines.

The Multi-line Text parameter feeds a single string value to the Quartz composition published input it is mapped to. Each line can be extracted by using the String Components patch and entering the Return character as the separator (type Option-Return).

Multi-line text parameters are available via on-screen UI in Final Cut Pro X and Motion 5. By default, a single button lets the user choose edit the text associated with the parameter. Users can hold down the Option key to import an existing text file instead.