Whether a purchase order cannot be requested without this column. Only valid on a
column whose applicable_models include purchase_orders (422 otherwise); removing
purchase_orders from them later switches it off. Only honoured when the caller has
custom_columns_manage: without it, it is silently dropped. Applies on create (the
order must be born with a value) and on edit (a value cannot be emptied); orders that
already existed are not changed.

Whether a reimbursement (document_type 29) cannot be requested without this column,
through the public reimbursement link or the web form (POST /v1/erp/payouts/payables).
Not enforced over WhatsApp. Only valid on a column whose applicable_models include
tradables (422 otherwise); removing tradables from them later switches it off. Only
honoured when the caller has custom_columns_manage: without it, it is silently dropped.
Applies only on create: a value can be emptied or corrected afterwards, and reimbursements
that already existed are not changed.