How to Add/associate Purchase Order number in CI Details of already existing or new workstation asset?

How to Add/associate Purchase Order number in CI Details of already existing or new workstation asset?

Hi,

I see there is Purchase Order number field in CI Details of an asset, for example a workstation asset.
But I cannot find any way to edit or add a purchase number to it.
Can anyone show me the steps? Thank you all...

We're using the latest ME ServiceDesk Plus version 9.1 build 9111.

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