|If I'm drafting a pattern, or significantly changing/morphing a commercial pattern, I assign the new pattern a number based on that day's date. For instance, the pattern number for today is 060705. If I happen (rarely) to make more than one pattern in a single day, I add a hyphen and the ordinal for that pattern. Example: 060705-1, 060705-2.
I put that number on every piece. I store the patterns in a gallon ziplock bag. I may even include a sketch or written description that I include in the bag.