> For the complete documentation index, see [llms.txt](https://docs.quilter.ai/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.quilter.ai/using-quilter/review-and-edit-constraints.md).

# Review and edit constraints

<figure><img src="/files/CZY0nil8q9JfDC0OS14R" alt=""><figcaption></figcaption></figure>

## Computed Constraints

### Differential Pairs

Based on the parameters from your stackup, Quilter uses Simbeor to calculate the correct trace width on each layer. Currently the frequency is assumed to be 1 GHz.

<figure><img src="/files/xR0WHQa76fNofYt0rbpe" alt=""><figcaption></figcaption></figure>

You can directly edit the width and gap here to override what we have calculated. This is especially useful if you have standard, precalculated values for your stackup.

### Power Nets

For each net and current you defined on the previous Comprehensions page, Quilter calculates the appropriate trace width to limit temperature rise to 20\*C, using the IPC-2221 definitions.

<figure><img src="/files/FRgvPib0aWTm8W8fLPXU" alt=""><figcaption></figcaption></figure>

## Define your own constraints

<figure><img src="/files/9NCNUOegzfuQZq7KqKq6" alt=""><figcaption></figcaption></figure>

### Net Widths by Layer

This allows you to specify trace width controls for nets. It is used rarely, and should probably be limited to nets that Quilter does not have another control for; e.g. you should not put in widths for your differential pairs here.

### Proximity Constraints

If Quilter does not have a placement control for your component type, you can add it here. One of the more common cases are protection diodes. You can also manually place components instead of using the placement constraints.


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