Anyone know where to start on the syntax for this?

I have changed Portal Personal Quotations/Sales Orders rule from the preset rule (for some reason I cannot post that because i can't seem to post more than one rule) to:

[('message_partner_ids', 'in', [user.partner_id.id])]

It seems to work but It would be good to get some feedback on this to make sure that I'm not making any rookie mistakes that may lead to a disaster.