For convenience, here are the quotes that most directly answer the above question:
"Effective December 15, 2026, the CA MUST implement Multi-Perspective Issuance Corroboration using at least five (5) remote Network Perspectives. The CA MUST ensure that [...] the remote Network Perspectives that corroborate the Primary Network Perspective fall within the service regions of at least two (2) distinct Regional Internet Registries."
"Network Perspectives are considered distinct when the straight-line distance between them is at least 500 km."
"Effective December 15, 2026, the CA MUST implement Multi-Perspective Issuance Corroboration using at least five (5) remote Network Perspectives. The CA MUST ensure that [...] the remote Network Perspectives that corroborate the Primary Network Perspective fall within the service regions of at least two (2) distinct Regional Internet Registries."
"Network Perspectives are considered distinct when the straight-line distance between them is at least 500 km."