dropOthers: Return the 'DROP_OTHERS' string that may be used in the 'outvars' vector for
RxODE/mrgsolve to drop all others variables that are usually output in the resulting data frame.
Description
Return the 'DROP_OTHERS' string that may be used in the 'outvars' vector for
RxODE/mrgsolve to drop all others variables that are usually output in the resulting data frame.