Marshal generate Packet with the ID and Fields.

NBT encode a value as Named Binary Tag.

Ary is used to send or receive the packet field like "Array of X" which has a count must be known from the context.

Packet define a net data package.

A Field is both FieldEncoder and FieldDecoder.

A FieldDecoder can Decode from minecraft protocol.

A FieldEncoder can be encode as minecraft protocol used.