Selling knitting-copyrights?

[tinydoom]

Hopefully this hasen't been addressed and I was just dense about finding a thread.  This is sort of along the lines of a copyright question....How much do you have to change a knitting pattern before you can sell it without infringing on someone elses work?  Are differnt colors or patterns enough? Slight changes in the construction?  Or maybe this does not matter at all?
Thanks!

[plainmabel]

Here's an article at Knitty that does a good job of covering this topic -- especially check out question #3 on the page though all of it is useful info:
http://www.knitty.com/ISSUEfall03/FEATcopyright.html

[Crafty Thistle]

Thanks for the link!  It will come in handy.