# resolution_columns

<table class=".origin_table">
    <tr>
        <td style="text-align: left; border-style: hidden">*function*  of [dascore.core._spool_inventory](`dascore.core._spool_inventory`)</td>
        <td style="text-align: right; border-style: hidden">[source](https://github.com/DASDAE/dascore/blob/dev/dascore/core/_spool_inventory.py#L263-L277)</td>
    </tr>
</table>

:::{.padded_bottom_10pt}

:::{.def_block}


<b>resolution_columns</b>(<br>
    &nbsp;&nbsp;&nbsp;&nbsp;frame: DataFrame
,<br>
)-> 'list | None'


:::

:::
Return the columns a relation resolves against an inventory with.

Resolution needs an identity and the instants to resolve it at, so a
relation missing either gets None here. A spool whose patches carry no
`acquisition_key` has no identity to offer, and one whose time axis
is not physical — lag times from a correlation, say — has no
instants, which is the same thing `Patch.enrich` refuses to guess at.

