Among them, 42 represents Hunan Province, 425 represents Yongzhou Postal District, 4257 represents Xintian Post Office, and 00 represents Xintian Postal Code. The area under Xintian County changes, and only the last two figures will change accordingly.

At present, the postal code adopted in China is "four levels and six codes". These six figures represent four levels: province (autonomous region, municipality directly under the central government), postal district, county (city) post and telecommunications bureau and delivery bureau (district).