# `ToonEx.Btoon.Constants`
[🔗](https://github.com/ohhi-vn/toon_ex/blob/v1.6.0/lib/toon_ex/btoon/constants.ex#L1)

Binary constants for the BTOON wire format.

BTOON is the binary transport encoding of the TOON data model (see
`Btoon`). This module defines the byte-level constants: the envelope
magic/version, flag bits, value type tags and typed-array / schema
element type selectors.

## Envelope

    +------------------+
    | Magic "BTON"     |  4 bytes
    +------------------+
    | Version          |  1 byte
    +------------------+
    | Flags            |  1 byte
    +------------------+
    | Reserved         |  2 bytes (MUST be zero)
    +------------------+
    | String Table     |  variable, zero-padded to a multiple of 8 bytes
    +------------------+
    | Schema           |  variable (only when the schema flag is set)
    +------------------+
    | Body             |  variable, 8-byte aligned
    +------------------+

## Flags

    bit0 (0x01) reserved
    bit1 (0x02) schema included
    bit2 (0x04) string table present
    bit3 (0x08) session dictionary active
    bit4 (0x10) no per-message string table
    bit5 (0x20) schema ID is UInt16
    bits6-7      reserved

# `element_array`

# `element_binary`

# `element_bool`

# `element_float32`

# `element_float64`

# `element_int8`

# `element_int16`

# `element_int32`

# `element_int64`

# `element_null`

# `element_object`

# `element_string`

# `element_uint8`

# `element_uint16`

# `element_uint32`

# `element_uint64`

# `flag_no_string_table`

# `flag_schema`

# `flag_schema_id_uint16`

# `flag_session_dictionary`

# `flag_string_table`

# `header_size`

# `int32_max`

# `int32_min`

# `magic`

# `reserved`

# `smallint_bias`

# `smallint_first`

# `smallint_last`

# `smallint_max`

# `smallint_min`

# `tag_array`

# `tag_binary`

# `tag_false`

# `tag_float32`

# `tag_float64`

# `tag_int32`

# `tag_int64`

# `tag_null`

# `tag_object`

# `tag_object_table`

# `tag_string`

# `tag_string_ref`

# `tag_true`

# `tag_typed_array`

# `type_tag`

```elixir
@spec type_tag(atom()) :: byte()
```

Returns the type tag for a BTOON primitive value tag.

# `version`

---

*Consult [api-reference.md](api-reference.md) for complete listing*