I've noticed in a number of examples that the following is occasionally used when working with tikz:
\tikzstyle{every picture}+=[remember picture]
When I search the documentation I can't find anything about this particular syntax. I can find no documentation for either \tikzstyle or +=.
I'm guessing that this means something like
\tikzset{every picture/.append style={remember picture}}
Could someone explain what this syntax is about and where I can find documentation for it?
