Indian Railways Zones (18 total):
| Code | Name | HQ |
|---|---|---|
| NR | Northern | New Delhi |
| NCR | North Central | Prayagraj |
| NWR | North Western | Jaipur |
| NER | North Eastern | Gorakhpur |
| NFR | Northeast Frontier | Maligaon |
| ER | Eastern | Kolkata |
| ECR | East Central | Hajipur |
| ECoR | East Coast | Bhubaneswar |
| SER | South Eastern | Kolkata |
| SECR | South East Central | Bilaspur |
| SR | Southern | Chennai |
| SCR | South Central | Secunderabad |
| SWR | South Western | Hubballi |
| CR | Central | Mumbai |
| WR | Western | Mumbai |
| WCR | West Central | Jabalpur |
| KR | Konkan | Belapur (CIDCO) |
| METRO | Kolkata Metro | Kolkata |
Each zone is further split into divisions (~70 total). Trains, stations, and PNR booking quotas are managed zone-wise.
First digit of PNR often hints at booking zone but not always reliable.