IO::Select and error_array

Hello everyone,

IO::Select works very well for me, but it still holds some mysteries for me. In particular: when will I get it to return due to an error?

More to the point, let's say I have:

read, write, error = IO::Select([some_io], [some_io], [some_io])

When will I get "error" to be something other than an empty array? I used it with sockets, and having the socket remotely closed apparently did not help provoke it.

/Christoffer