# block_header · FT4 Rell API · Chromia Docs (concept)

> struct block_ header {
 blockchain_ rid: byte_ array;
 previous_ block_ rid: byte_ array;
 merkle_ root_ hash: byte_ array;
 timestamp: integer;
 height: i

Source: https://docs.chromia.com/pages/ft4-rell/-f-t4-library/lib.iccf/block_header/

STRUCT

# block\_header

```signature
struct block_header {
 blockchain_rid: byte_array;
 previous_block_rid: byte_array;
 merkle_root_hash: byte_array;
 timestamp: integer;
 height: integer;
 dependencies: gtv;
 extra: map<text, gtv>;
}
```

[Source](https://gitlab.com/chromaway/ft4-lib/src/development/rell/src/lib/iccf/module.rell#lines-12)

[View this page on docs.chromia.com](https://docs.chromia.com/pages/ft4-rell/-f-t4%20-library/lib.iccf/block_header/index.html)Generated API reference, mirrored from the live docs