Inline data is optional. If no inline data is present, it is encoded as 0 bytes.

| Entry               | Encoding                    | Content
| --------------------|-----------------------------|----------------------------------------
| xlMetaInlineDataVer | byte                        | version identifier
| id -> data          | msgp `map[string][]byte`      | Map of string id -> byte content

Currently only xlMetaInlineDataVer == 1 exists.

```go
// hashes the key returning an integer.
func sipHashMod(key string, cardinality int, id [16]byte) int {
        if cardinality <= 0 {
                return -1
        }
        sip := siphash.New(id[:])
        sip.Write([]byte(key))
        return int(sip.Sum64() % uint64(cardinality))
}
```