What is a "baton" from subversion sources?

[Grigory Petrov]

Hello.

I'm learning subversion API right now and examining it's source code and 
examples. It's a lot of things in subversion source code that is called 
a "baton". For example, svn_cmdline_create_auth_baton() create "auth 
baton", and callbacks takes callback function pointer and, again, 
batons. I never heard of a term "baton" related to the programming. That 
is the "baton" concept subversion source code refers to? Maybe i can 
read somewhere about "batons" used in programming? Or is it a well-known 
term of some origin?

Best,
Grigory.