dalet/specification/daletl.md

# Daletl specification for Dalet v1.0-preview

## Data format

Daletl must be serialized as [MessagePack](https://github.com/msgpack/msgpack/blob/master/spec.md). All data transfer between server and client is done in this format.

### Root

Daletl root is array of tags. For convenience, we will use the json5 representation of the data.

```json5
[]
```

### Tag

All tags specification is in [Tags](./tags.md).

Each tag may be one of three types:

#### Data Representation

##### As array of 1-3 elements

1. Tag id
2. Tag body (optional if argument not specified, if argument specified it must be null)
3. Tag argument (optional)

Tag id is integer number.

Body can be only a string, null, array of tags or tag (equals to array of tags with 1 tag).

Argument can be number or string.

###### Heading example

```json5
[1, "This is heading", 1]
```

###### Unordered list example

```json5
[
  4,
  [
    [0, "Item 1"],
    [0, "Item 2"],
  ],
]
```

##### As string

String becomes element tag.

```json5
"Element"
```

equals to

```json5
[0, "Element"]
```

##### As array of tags

If array not started with a number. The implication is that this turns into an “element” tag

```json5
["Element", [1, "Heading"]]
```

equals to

```json5
[
  0,
  [
    [0, "Element"],
    [1, "Heading"],
  ],
]
```