Samāʿ: hearing the teacher's spoken text; “samiʿtu” is explicit.
ʿArḍ: reading to the teacher or hearing such a reading; “qaraʾtu ʿalayhi” or “quriʾa ʿalayhi wa-anā asmaʿ.”
Ijāzah: authorization; no direct hearing is necessarily established.
Munāwalah: physical handover; distinguish with and without permission.
Mukātabah: a teacher sends the written report; verify attribution.
Iʿlām: the teacher identifies a report as his own; permission remains a separate issue.
Waṣiyyah: a bequest or assignment of books; custody is not narration.
Wijādah: finding another scholar's writing; do not claim direct hearing.
Different links of a single isnād may involve different means of acquisition. Each must be documented according to what actually occurred, not forced into a single uniform formula.