Best dvd results what are pi pif reading curve

As I have read reviews on different burners I have seen graphs from nero cd/dvd speed. The graphs are pi, pif and reading curves. What do they mean and what would the graphs look like if it were an near perfect burn?

What are pi errors?
What are pif errors?
How do these errors effect the way the dvd plays on dvd players?

Try doing a search on it, but in short p1 errors are where the DVD reader makse a mistake, p1 failures are where the reader can’t work out what the hell is supposed to be there. Too many errors and you won’t be able to watch the DVD, but the errors you detect and how it plays varies with each DVD drive. (CD-DVD speed terms)

This sticky will tell you more:

http://club.cdfreaks.com/showthread.php?t=80545