Select multiple values for 1 attribute Merged

Would be a great help if we would be able to have attributes that allow multiple values to be selected.
Now, we need to define a lot of Yes/No attributes.
This duplication of attributes also makes reports and dashboards more complicated.

Example: now we have attributes:
IS: Yes/No
IIS: Yes/No
NIS: Yes/No

where in fact this is known by our users as possible values of the 'study type'.
Would be good that we can define 1 attribute 'study type', which can then have as selected values for example: IS, NIS