How far do we go within the definition of 'variation' before we've created a whole new knot?
How many 'hearts' and in what configuration/shapes before we consider ourselves as having an entirely new creature?
For me, I like to consider knot "families" based on the tying method and the appearance.
So, the Chinese button knot (2 strand diamond knot, knife lanyard, bosun's whistle, etc) using the able seaman method (
http://www.chineseknotting.org/button/howto2/) extends (theoretically) infinitely in length (
http://www.chineseknotting.org/projects/button-necklace.jpg), but the 4 strand diamond knot (
http://www.chineseknotting.org/projects/knotty/Y-button-stamp.jpg) looks exactly the same (if you don't look at the ends). Then there's the one strand button knot (
http://www.stellaceleste.com/htm/knots/buttonknot.htm) which is... some variety of turk's head? I consider these all to be variations of the same knot although they all use different tying methods.
Consider the cloverleaf (flower, dragonfly, etc) knot (
http://www.chineseknotting.org/flower/). The obvious first variation is increasing the number of petals (
http://www.chineseknotting.org/flower/flower8-big.jpg). But if you were to take the basic knot and then tie a compound knot with them like the ru-yi (
http://www.chineseknotting.org/flower/ruyi/ru-yi-bw.jpg) and then decide to connect them directly you get into mystic (pan chang) territory (
http://www.knottynotions.com/mystic/assembly). The 4 petal cloverleaf being very obviously the unit version of the pan chang. Just the cartesian version of the pan chang can take almost any flat solid shape, some of which have names (like stone chime) and others not so much (I have seen someone do the map of Taiwan with a big pan chang knot) but there are also triangular variations (
http://books.google.ca/books?id=bcZpZDAbsFMC&pg=PA50&lpg=PA50&dq=triangular+pan+chang+knot&source=bl&ots=yqM96zC219&sig=4io5qGb1ae-ncb32qHW2QxKGMP8&hl=en&ei=qAuZTMuOH4j6swONzYjQDA&sa=X&oi=book_result&ct=result&resnum=1&ved=0CBQQ6AEwAA#v=onepage&q=triangular%20pan%20chang%20knot&f=false). Backing up to the cloverleaf, a little variation on the interlacing of the structural centre parts will give you the stellar (constellation) knot (
http://www.chineseknotting.org/stellar/). And that's just one structural loop variation, there are many more.
Going further afield, consider the basic square knot/macrame knot (
http://www.chineseknotting.org/square/square.jpg). Then consider the creeper knot (
http://www.chineseknotting.org/square/howto-creeper/). Then consider the plafond itself. Variations on a theme?
Even the very basic simple/overhand knot. Is the grinner/barrel/blood knot it's own thing?
I don't think so, but...
Hmmmm, have I gone off-topic?

I think the line between variation and own thing (at least in the decorative field, for practical there's the functionality issue) is an eye of the beholder/hand of the maker/pen of the author issue.
ps. thanks JD.
