Proven acceptable range (PAR)

A characterized range of a process parameter within which operation, with the other parameters held constant, produces material meeting the relevant quality criteria (ICH Q8). It is wider than the normal operating range used in routine production. Because PARs are usually studied one parameter at a time, they do not by themselves form a design space. The Japanese term literally means 'acceptable range' and can be used loosely, so check that a range labeled this way was actually demonstrated with data. Operating outside a PAR is a deviation with possible regulatory consequences.