bar.len(optional)States the length of barlines in virtual units. The value must be greater than 0 and
is typically equal to 2 times (the number of staff lines - 1); e.g., a value of '8'
Value is a decimal number.
bar.method(optional)Records the method of barring.
Value conforms to data.BARMETHOD.
bar.place(optional)Denotes the staff location of bar lines, if the length is non-standard; that is, not
equal to 2 times (the number of staff lines - 1).
Value conforms to data.STAFFLOC.