> For the complete documentation index, see [llms.txt](https://docs.zingg.ai/0.3.3/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.zingg.ai/0.3.3/definingown.md).

# Improving Accuracy By Defining Own Functions

You can add your own [blocking functions](https://github.com/zinggAI/zingg/tree/main/core/src/main/java/zingg/hash) which will be evaluated by Zingg to build the [blocking tree.](/0.3.3/zmodels.md)

These business specific blocking functions go into [Hash Functions](https://github.com/zinggAI/zingg/tree/main/core/src/main/java/zingg/hash) and need to be added to [HashFunctionRegistry](https://github.com/zinggAI/zingg/blob/main/core/src/main/java/zingg/hash/HashFunctionRegistry.java) and [hash functions config](https://github.com/zinggAI/zingg/blob/main/core/src/main/resources/hashFunctions.json)

Also, for similarity, you can define your own measures. Each dataType has predefined features, for example [String](https://github.com/zinggAI/zingg/blob/main/core/src/main/java/zingg/feature/StringFeature.java) fuzzy type is configured for affine and jaro

You can define your own [comparisons](https://github.com/zinggAI/zingg/tree/main/core/src/main/java/zingg/similarity/function) and use them