Access to special accounts with dynamically-updated data.
Sysvars are special accounts that contain dynamically-updated data about the
network cluster, the blockchain history, and the executing transaction. Each
sysvar is defined in its own crate. The [`clock`], [`epoch_schedule`],
[`instructions`], and [`rent`] sysvars are most useful to on-chain programs.
[`clock`]: https://docs.rs/solana-clock/latest
[`epoch_schedule`]: https://docs.rs/solana-epoch-schedule/latest
[`instructions`]: https://docs.rs/solana-program/latest/solana_program/sysvar/instructions
[`rent`]: https://docs.rs/solana-rent/latest
All sysvar accounts are owned by the account identified by [`solana_sysvar::ID`].
[`solana_sysvar::ID`]: crate::ID
For more details see the Solana [documentation on sysvars][sysvardoc].
[sysvardoc]: https://docs.solanalabs.com/runtime/sysvars