| Number | Bits | Description | Reference |
| 0 | 16 | Reserved | RFC1930] |
| 1 - 23455 | 16 | Public ASN's | |
| 23456 | 16 | Reserved for AS Pool Transition | RFC6793] |
| 23457 - 64534 | 16 | Public ASN's | |
| 64000 - 64495 | 16 | Reserved by IANA | |
| 64496 - 64511 | 16 | Reserved for use in documentation/sample code | RFC5398] |
| 64512 - 65534 | 16 | Reserved for Private Use | |
| 65535 | 16 | Reserved | |
| 65536 - 65551 | 32 | Reserved for use in documentation and sample code | RFC4893]RFC5398] |
| 65552 - 131071 | 32 | Reserved | |
| 131072 - 4199999999 | 32 | Public 32-bit ASN's | |
| 4200000000 - 4294967294 | 32 | Reserved for Private Use | RFC6996] |
| 4294967295 | 32 | Reserved | |