How can I know read-only attrs?

[Tomàs Núñez Lirola <tomas@criptos.com>]

Hi again
I've been searching a way to know which attributes from a node are
read/write, and which are read-only. For what I've seen, there is no way
to know this except by trying to modify the attribute and waiting for the
server's answer.

Am I wrong? Is there a way to know if the attrs are read/write before
writing them?

Thanks in advance
Tomàs