What's the bargaining space in a post-doc employment contract - in the Netherlands? Motivation

I'm soon going to start a Post-Doc in the Netherlands. The labor laws are different from where I did my Ph.D. work; the academic culture is somewhat different; the unionization situation is different; etc.

So, I've gotten the informal offer over email, and I'm now expecting the formal contract offer. I already have a copy of the collective employment agreement which covers post-doctoral researchers where I'll be working. 

When I did my PhD, like I said, the situation was quite different - plus, I didn't actually get to sign any contract and no bargaining was involved. But now there might be some bargaining (although I'm not sure to what extent as employment conditions are mostly standardized).

The actual question

My question is: What are, in your experience or opinion are points that are possible/useful to bargain about in the individualized contract? If you can, please give an example of better vs worse options for the same point. Long lists with less details are also quite ok by me :-)

Examples

(some more academia-specific and some more generic)


The extent to which the academic institute controls copyrights to your discoveries: Partial copyright in your works / Institute controls everything / Automatic publication under free license.
The extent to which you can be required to perform duties other than your chosen specific personal research: Not at all / At their discretion / Upto x% of the work week
Funding for attending conferences abroad


Notes


Somewhat-related question: What questions should I ask when I visit labs for potential post-doc employment?
Please answer even if your experience does not regard the Netherlands. I'm particularly interested in inter-national differences, because the prevalence of alternatives elsewhere is a point I can use in bargaining.
Legally, as far as I understand, it is not possible to negotiate new terms that contradict the terms of the applicable collective labour agreements in the Netherlands. Many labour agreements however leave some room for negotiation, see e.g. Appendix 3 in the file you linked. In practice however there I would not expect there to be much room.

As for your example questions:


As Bill Barth pointed out, Section 1.9 arranges IP ownership, and indeed the employer owns everything. See also point 4 of Article 1.9.3. I don't see much room here for negotiation.
This is not part of the collective agreement. Your contract may have certain provisions, for example the amount of teaching (if applicable). You should discuss this with your supervisor/boss on what is expected and how much freedom you will have. Here there may be some room for negotiation.
Again, this is something the supervisor can answer. It depends on how much budget the group has available, or if your work is part of a grant funded project, how much there is available there.