This is an optional feature of Text Areas. When this is enabled, this feature allows you to hop between every six asterisks in the Text Area to make your edits. You can hop by clicking on the "Fillable" button or by pressing CTRL plus the left or right arrow. The fillable text can just be 6 (six) asterisks or all the text between two sets of 3 (three) asterisks.
Note for example below: To switch views between the Active Form and Markup Code, click on "View" in the upper right of this page. Then choose "Form" to see the Active Form or choose "Markup" to reveal the Markup Code.
Example 1: [textarea name="variable_1" memo="sample text area" default="enter ***text*** here or here****** or ******" fillable="true"]