[xml] custom payload on xmlNode* objects?

[Martijn Faassen <faassen infrae com>]

Hi there,

I have been looking at the xmlNode* structure definition today to see 
whether there is a way to stuff a pointer onto it. This because I am 
exploring an idea of having backpointers to Python (object) 
datastructures in the nodes themselves in the design of the lxml library.

One candidate is the psvi field. What in libxml2 would break if I use 
this for my custom data?

For my purposes, I mainly need this extra pointer on elements. Is the 
content field in use on element nodes, or could it safely be coopted? If 
it is in use, what is it?

Thanks,

Martijn