The list in SPO 51 lists the same equipment as the list on the QRH under “Required Equipment for RNAV Procedures”. On the QRH you can see it says “Before IAF”. For loss of equipment after crossing the IAF you can check FCOM-NOR-SOP-18-C “Management of degraded navigation”.
Remember that you only need to check those lists (particularly the one on the QRH) if you lose equipment after dispatch. For deferred equipment, the MEL will tell you your applicable restrictions.