Ellipses (...)

Use the ellipsis in UI text to indicate that additional information or an intermediate step is required before the action can be completed. For example, when users click New Report ..., they need to select a report type before they can create the report.
Use an ellipsis in ghost text to indicate that users can take action.
Refer to user interface elements using the element's exact label (including any end punctuation, such as an ellipsis). For example: Click Add... to browse for files on your local computer.
In a quoted passage, use an ellipsis to indicate any omission of text.

Salesforce Style Guide for Documentation and User Interface Text