PIL internally supports parameters with values with specify vectors with either fixed or variable number of elements. This works for parameter types: integer, real and real4. The parameter itself has to be of type string (type stored in parameter file). Thus it can be read as either string (by calling PILGetString) or vector of values (by calling PILGetxxxVector or PILGetxxxVarVector). See description of PILGetxxxVector or PILGetxxxVarVector functions for more details.