From LimeSurvey Manual
Slider left/right text separator (slider_separator)
This question attribute sets the separator used to display text labels on the left and right side of the slider.
Let's suppose that you want to find out from your respondents which fruit they enjoy eating. First, set the text separator in the "slider left/right text separator" field - we will use in this example a simple vertical bar: " | ".
Then format your subquestions to read:
- Any character
- Import the following question example into your installation to see how such a question would look like: Separator_multiple_numerical_input_question_type.zip.