Whitepaper - Factom With Cover

Factom System Overview
Factom is constructed from a set of layered data structures
Factom is constructed of a hierarchical set of blocks, with the highest being Directory Blocks.
They constitute a micro-chain, consisting primarily of compact references. To keep the size
small, each reference in the Directory Block is just a hash of the Entry Block plus its ChainID.
These Entry Blocks have references which point to all the Entries with a particular ChainID
which arrived during a time period. The Entry Block for a Chain ID is also part of a micro-chain.
The bulk of the data in Factom is at the leaves, the Entries themselves. These hierarchical data
structures are rendered unchangeable by Bitcoin’s hashpower. They can be conceptualized as
different layers.
The layers and concepts in the Factom system are:
1) Directory Layer -- Organizes the Merkle Roots of Entry Blocks
2) Entry Block Layer -- Organizes references to Entries
3) Entries -- Contains an Application's raw data or a hash of its private data
4) Chains -- Grouping of Entries specific to an Application
Directory Layer: How the Directory Layer Organizes Merkle Roots
The Directory layer is the first level of hierarchy in the Factom system. It defines which Entry
ChainIDs have been updated during the time period covered by a Directory Block. (ChainIDs
identify the user’s Chain of Entries; the generation of the ChainID is discussed later.) It mainly
consists of a list pairing a ChainID and the Merkle root of the Entry Block containing data for that
ChainID.
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