> For the complete documentation index, see [llms.txt](https://hacd-labs.gitbook.io/hacd-labs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://hacd-labs.gitbook.io/hacd-labs/hacd-hacash-diamond/editor.md). # What is the HACD?

HACD (Hacash Diamond) stands as the world’s first implementation of the HST framework. HACD introduces a unique approach to HST with a total supply of 16,777,216 Base Tokens, issued through a Proof-of-Work (PoW) mechanism. These tokens are generated via hashing power and on-chain bidding, with a maximum of 58 Base Tokens produced daily. The mining difficulty increases over time, resulting in only approximately 0.6% of the total supply being issued over the past 6 years since its inception. Each HACD Base Token is uniquely identified by a 6-letter code and a serial number. For instance, the first HACD, produced on May 16, 2019 is labeled the identifier NHMYYM and serial number 1. With a storage capacity of 12.5 KB, each Base Token manages Stack Tokens and stores relevant data, aligning with HST’s foundational requirements. HACD operates on the Hacash blockchain, utilizing an indexer-based system to track token interactions efficiently, eliminating the need for traditional smart contracts.

HACD’s Stack Protocol supports two types of Stack Tokens: * **Mutable Stack Token:** This type allows the issuance of FT, NFT, or SFT, with the flexibility to modify token quantities. Issuance and minting require HAC (the native currency of Hacash) as a transaction fee, with common issuance methods including auctions and minting. This enables dynamic market applications, such as adjustable in-game currencies or evolving digital assets.

* **Immutable Stack Token**: Requiring an upgrade to the Hacash mainnet, this type becomes unalterable once set. It is primarily used for generative art NFTs, such as HACD’s visualized diamonds, with a total supply matching the 16.77 million Base Tokens. These diamonds are created using visualization genes, resulting in 9 distinct shapes, 8 of which are special diamonds with a 3% probability of occurrence, adding unique value to the ecosystem.

HACD demonstrates HST’s potential, allowing users can issue and manage Stack Tokens within HACD and leverage its unified structure to explore innovative applications across various industries.