Q22 BUS parity check?

[9000 VAX]

Hello,
  I read the Q22 specification (search "Q22 specification" on this page:
http://www.chd.dyndns.org/qbus_ide/ ) but the parity check function is still
not clear to me. My questions are,
1. Is there parity check when interrupt vector is read ?
2. Is there parity check if IO page is read?
3. What is the polarity of the parity bit?

Those questions are not answered from the specification. Any expert here?
Thanks

vax, 9000