Hi @Matolab,
Try this out! Maybe this is what you are looking for as shown in the image below:
In the survey tab of the xlsform form:
In the choices tab of the xlsform form:
Data collection screen as seen in Enketo (when it is filled wrongly): Here a user tries to enter more than 3 choices.
Data collection screen as seen in Enketo (when it is filled correctly): Here a user tries to enter less then or equal to 3 choices i.e. greater than 0 and less than or equal to 3.
Reference xlsform:
ICPC (mat).xlsx (22.1 KB)
Have a great day!