> For the complete documentation index, see [llms.txt](https://docs.internetobject.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.internetobject.org/schema-definition-language.md).

# Schema Definition Language

- [Overview](https://docs.internetobject.org/schema-definition-language/internet-object-schema.md): How Internet Object schemas describe the shape of data, and the pieces that make them up.
- [Schema Representation](https://docs.internetobject.org/schema-definition-language/schema-representation.md): How a schema is written and how data is mapped to it — open/closed, positional/keyed, and the default schema.
- [Schema Data Types](https://docs.internetobject.org/schema-definition-language/data-types.md): The Internet Object schema type system — base types, shortcuts, and TypeDefs.
- [Any](https://docs.internetobject.org/schema-definition-language/data-types/any.md): The any type — accepts any value, optionally constrained by anyOf or choices.
- [String Types](https://docs.internetobject.org/schema-definition-language/data-types/string.md): The string type and its email and url shortcuts.
- [Email](https://docs.internetobject.org/schema-definition-language/data-types/string/email.md): The email type — a string validated as an email address.
- [URL](https://docs.internetobject.org/schema-definition-language/data-types/string/url.md): The url type — a string validated as a URL.
- [Numeric Types](https://docs.internetobject.org/schema-definition-language/data-types/number.md): The number type and its family of integer, unsigned, and float shortcuts.
- [BigInt](https://docs.internetobject.org/schema-definition-language/data-types/bigint.md): The bigint type — arbitrary-precision integers.
- [Decimal](https://docs.internetobject.org/schema-definition-language/data-types/decimal.md): The decimal type — fixed-precision decimal numbers.
- [Date and Time](https://docs.internetobject.org/schema-definition-language/data-types/date-and-time.md): The datetime, date, and time types.
- [Binary](https://docs.internetobject.org/schema-definition-language/data-types/binary.md): The binary type — byte data written as base64.
- [Object (SchemaDef)](https://docs.internetobject.org/schema-definition-language/data-types/object.md): The object type — structured key/value data described by a SchemaDef.
- [Array](https://docs.internetobject.org/schema-definition-language/data-types/array.md): The array type — ordered, typed collections of values.
- [Bool](https://docs.internetobject.org/schema-definition-language/data-types/bool.md): The bool type — true/false values.
- [Advanced Schema Concepts](https://docs.internetobject.org/schema-definition-language/advanced-schema-concepts.md)
- [TypeDef](https://docs.internetobject.org/schema-definition-language/advanced-schema-concepts/typedef.md): TypeDef — the fixed option contract that every MemberDef of a type is validated against.
- [MemberDef](https://docs.internetobject.org/schema-definition-language/advanced-schema-concepts/memberdef.md): MemberDef — defining one member's type, constraints, and optional/nullable/default behavior.
- [Open & Dynamic Schemas](https://docs.internetobject.org/schema-definition-language/advanced-schema-concepts/dynamic-schema.md): Open and dynamic schemas — accepting extra fields with the \* marker.
- [Union Types (anyOf)](https://docs.internetobject.org/schema-definition-language/advanced-schema-concepts/union-types.md): Members that accept more than one type, via anyOf.
- [Composition & Reuse](https://docs.internetobject.org/schema-definition-language/advanced-schema-concepts/composition.md): Composing and reusing schemas through references.


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