Hover forms - how do they link to actual object

Hi all

The little red dot in DD items means there is a hover form attached.
I see 2 tables in P958973 etc, but I can't see how they then link to actual P object form.

Example
JDE_CUSTOMERHOVER_SHAN is one as is JDE_NOHOVER_LITM
but where is the link to the form they open stored. I suspect its the UID type field linking F958973 and F958974 linking off to somewhere else, but we haven't updated our XREF yet for me to check

Thanks

John
Than