Linked from
The 9 pages that link to Upasampadā, each with the reason it gives.
SanghaBroader topic: Full ordination establishes formal membership in the monastic Sangha.
VinayaBroader topic: Vinaya specifies the eligibility and communal procedure for full ordination.
BhikkhunīBroader topic: This ordination confers the status named by bhikkhunī.
BhikkhuBroader topic: This ceremony confers the status meant by bhikkhu.