# Adding Z positioning restraints to the JSON parameter file

**URL:** <https://ask.bioexcel.eu/t/adding-z-positioning-restraints-to-the-json-parameter-file/3685>\
**Category:** HADDOCK\
**Created:** [April 19, 2022, 7:19pm UTC](https://ask.bioexcel.eu/t/adding-z-positioning-restraints-to-the-json-parameter-file/3685 "2022-04-19T19:19:41Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![sgcondon](https://avatars.discourse-cdn.com/v4/letter/s/4da419/32.png) [@sgcondon](https://ask.bioexcel.eu/u/sgcondon)\
**Post date:** [April 19, 2022, 7:19pm UTC](https://ask.bioexcel.eu/t/adding-z-positioning-restraints-to-the-json-parameter-file/3685/1 "2022-04-19T19:19:41Z")

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I’m interested in performing some docking in which the z-coordinates of my molecules are restrained. The documentation shows how to add these restraints to the run.cns file ([HADDOCK2.4 manual - run.cns parameters – Bonvin Lab](https://www.bonvinlab.org/software/haddock2.4/run/#membrane-z-positioning-restraints)), but I’m at a bit of a loss when trying to make the equivalent modifications in the job\_params.json file. Specifying the zresmax, zresmin, zres\_on, and numzres parameters is straightforward, but how do I add in the segments to be restrained? Thanks for your help!

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**Author:** ![amjjbonvin](https://dub1.discourse-cdn.com/flex013/user_avatar/ask.bioexcel.eu/amjjbonvin/32/23_2.png) [@amjjbonvin](https://ask.bioexcel.eu/u/amjjbonvin)\
**Post date:** [April 20, 2022, 6:50am UTC](https://ask.bioexcel.eu/t/adding-z-positioning-restraints-to-the-json-parameter-file/3685/2 "2022-04-20T06:50:00Z")

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This is a rather unsupported feature on the server.  
It is indeed defined in `run.cns` but never properly benchmarked, which is why it is not yet available on the server.