NBT format

The Named Binary Tag (NBT) is a tree data structure used by Minecraft in many save files to store arbitrary data. The format comprises a handful of tags. Tags have a numeric type ID, a name, and a payload. A user-accessible version in the form of strings is the stringified Named Binary Tag (SNBT) format.

String Named Binary Tag (SNBT), is the stringified representation of any NBT data tag. It is often used in commands in Java Edition. The root tag is most commonly a map, also known as a compound holding key-value pairs enclosed in curly braces (see below for details). An example of SNBT is specifying complex data for entities with commands.

Quote enclosure is optional if the string contains only 0-9, A-Z, a-z, _, -, ., and + characters, and if the string does not begin with 0-9, -, ., or +.