Hi,
I've just updated the lpe-knot, to let the user choose the orientation of each crossing independantly.
Please test and report bugs. (yes there are some! I know one of them at least: it won't work for groups, and cannot be shared by different objects)

Writing this, I came to an issue I don't know how to solve:

Up to know, lpes are supposed to be black-boxes taking any path as input, and giving an other path as output. You can eventually tune the behaviour of the black box using some parameters, which are always attached to the blackbox, and do not depend on the input.
Some effect however require the storage of path-specific information. lpe-knot is an exemple: for each crossing in the path, we need to attach an orientation. This has to be somehow stored in svg, but highly depends on the path. In particular, this information canot be shared by different paths :-(
I guess other cases will show up.

Did we already meet and solve this? Any clue about the way this could be handled?

One way could be to systematically duplicate the lpe when trying to use it on several objects (for groups or when pasting).
What do you think?

Best regards, JF.