Which table and field is Related Object

Dear All,
I use Dolibarr 3.5.2
I need to print in my customers orders .odt the No of Proposal from which it is created
and in my Invoices the No of customer’s order from which it is created.

When it is on the display I see it in the bottom line Related commercial proposals but which is this field and in which table pls.
See attached screenshot.
in llx_facture and llx_propoale and llx_commande I didn’t find such info.

Thanks in advance.

Dear DoliDev,
Thanks to all.
I found this is table: llx element element
http://wiki.dolibarr.org/index.php/Table_llx_element_element
So, could you be so kind to help me - how to use data from this table and to have a result in a tag for my .odt template. I want when printing ORDER forms to fill in it related PROPALE #. When Printing INVOICE forms to fill in related ORDER #.
I don’t need and don’t use .pdf - only .odt templates.