Constant FEE_DOCUMENT_TTL_VERSION1 

pub const FEE_DOCUMENT_TTL_VERSION1: FeeDocumentTtlVersion;

Introduced with protocol version 14 (4.2), the first version that parses the document type ttl keyword; every fee schedule references it, and none before 14 reads it.

The per-byte prices are pro rata of the first year of perpetual storage: 27,000 credits per byte (storage_disk_usage_credit_per_byte), of which the distribution table pays 5% out in the first year (40 mainnet epochs of 9.125 days), so about 3.7 credits per byte per day and 33.75 per byte per 9.125 day period, rounded up. A document of a one-year ttl therefore pays about what a permanent document deleted after a year keeps paying net of its refund. The period is mainnet’s epoch length, fixed here so a network configured with shorter epochs does not multiply the price.