Pali abhirūhana; cf. abhirohaṇa; to Skt. abhirohati),
mounting, ascent: Mv ii.289.8 abhirūha(na)saṃpannāḥ
(sattvāḥ, sc. Bodhisattvas; in Pali lit. or fig. of mounting
as on a ship, esp. by a gangplank; so presumably here,
fig. furnishing a gangplank to salvation).