The complex’s departments

The complex’s departments and each one’s schools, with `viewer` — where the person stands (`reach` what they reach, or null for the whole tree). Every tree read is already fenced to the person’s department.

• Rate Limit: LIGHT
  How heavily this call counts against your quota: LIGHT < MODERATE < HEAVY.
• Permission needed: entity.hierarchy.read
  The scope the tenant must grant your app before this call is allowed.
• Reference Code: srv_aaa5
  A stable identifier for this endpoint — quote it to support to speed up tracing.

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