Minecraft Snbt Format

SNBT Format

SNBT (Stringified Named Binary Tag) is the text form of NBT, used in data-modifying commands and .snbt files (UTF-8). It resembles NBT but is not identical to it. /data get prints syntax-highlighted SNBT ("pretty-printed"); the nbt text component type can also output highlighted SNBT.

Data Types

Numbers

Underscores may separate digits (0b10_01, 0xAB_CD, 1_2.3_4__5f, 1_2e3_4) but not at the start/end.

• Floats (IEEE 754): no-suffix decimals are doubles (1.2). Fractional or integer parts may be omitted (.1, 1.). Scientific notation allowed (1.2e3, 12000e-1 → 1200.0). Out-of-range (→ infinity) values like 1e1000 are invalid. NaN/Inf/hex floats unsupported.
• Integers: no-suffix integers are ints (123). Hex 0x and binary 0b prefixes allowed (0xCAFE, 0b101). Integers (except 0) must not start with 0 (octal ambiguity).
• Booleans: SNBT booleans are bytes limited to 0/1; true/false (case-insensitive) → 1b/0b.

Type Suffixes

First letters, case-insensitive: b byte, s short, i int, l long (floats: f, d). Optionally prefixed with s/S (signed) or u/U (unsigned) — e.g. 123sb = signed byte 123. Signed values store as two's complement; the prefix only affects parse ranges (240sb fails; 240ub == -16sb). Decimal numbers default to signed; hex/binary default to unsigned. Because b is a valid hex digit, hex bytes need the explicit prefix (0x11ub, 0x11sb).

Strings

• Quoted: "test" or 'test'; the same quote inside must be escaped ("\"test" valid, ""test" invalid).
• Unquoted: test — only 0-9, a-zA-Z, ., _, +, -; must not start with a digit, ., +, or - (numeric conflicts); true/false parse as booleans.
• Escape sequences in quoted strings: \", ', \\, \/, \b, \f, \n, \r, \t, \uXXXX (Unicode escapes).

Arrays

[B;...], [I;...], [L;...]: values without suffixes take the array's type ([B;1,2] == [B;1b,2b]); smaller types are widened ([I;1b,2s,3] == [I;1i,2i,3i]).

Lists

Heterogeneous elements allowed (['', {text:"hello"}, 123]; some contexts still require homogeneity). One trailing comma allowed after a valid element ([1,2,]; [,], [1,,] invalid). Nesting ≤ 512 levels.

Compounds

Key-value maps ({a:b}). One trailing comma allowed ({a:b,}; {,}, {a:b,,} invalid). Nesting ≤ 512 levels.

SNBT Operations

Function-like syntax <name>(<arg1>, ...) evaluated at parse time (cannot be preserved or syntax-highlighted):

• bool(arg) — exactly one numeric or boolean argument: booleans pass through; numbers → true if non-zero. bool(true) → true; bool(0) → false; bool("foo") → error.
• uuid(str) — one dash-formatted UUID hex string → int array: uuid("f81d4fae-7dec-11d0-a765-00a0c91e6bf6") → [I; -132296786, 2112623056, -1486552928, -920753162].

Conversion

SNBT is never stored directly — it converts to NBT, then to program objects (see the nbt-format skill).