BinaryString blobs

Roblox DOM and (de)serialization implementation in Rust

BinaryString blobs

Certain properties (such as Instance.Tags) are serialized as blobs of binary data. These blobs are represented by Roblox as BinaryString values. The format used for a given property is entirely custom and must be known to read and write values to that property.

This document serves as unofficial documentation for potential BinaryString values, describing their structure.


Values of this type are encoded using the BinaryString data type in the XML format. In the binary file format, they are encoded as String values.


The following is a list of BinaryString blobs and their formatting. For clarity, the name of the property using a blob is used as the header name, and the class it is a part of is listed beneath the header.

When a format is sufficiently complex, it may be stored in its own document for clarity.


Used By: Instance.AttributesSerialize

This blob is used to serialize attributes. Due to the complexity of the format, a specification is located here.


Used By: Terrain.MaterialColors

This blob is used to serialize MaterialColors.

MaterialColors is stored internally as 69 bytes, which is read a sequence of 23 three-byte arrays. Each of these arrays represents the red, green, and blue components of the color of a specific variant of the Material enum.

These values are in a fixed order. The following table describes what byte (from the beginning of the blob) corresponds to what component of what Material enum value.

RR GG BB Material Variant
00 01 02 None (reserved)
03 04 05 None (reserved)
06 07 08 Grass
09 10 11 Slate
12 13 14 Concrete
15 16 17 Brick
18 19 20 Sand
21 22 23 WoodPlanks
24 25 26 Rock
27 28 29 Glacier
30 31 32 Snow
33 34 35 Sandstone
36 37 38 Mud
39 40 41 Basalt
42 43 44 Ground
45 46 47 CrackedLava
48 49 50 Asphalt
51 52 53 Cobblestone
54 55 56 Ice
57 58 59 LeafyGrass
60 61 62 Salt
63 64 65 Limestone
66 67 68 Pavement

The first two rows appear to be unused at this moment and should always be written as 00 00 00 to preserve compatibility.


Used By: Instance.Tags

This blob is used to serialize CollectionService tags for an Instance.

Tags is stored as an array of bytes representing every tag on an Instance. The array is delineated using 00. Otherwise, the literal bytes of the tag are written.

As an example, an Instance that had the tags Hello, from, and Rojo would have them serialized as follows:

48 65 6C 6C 6F 00 66 72 6F 6D 00 52 6F 6A 6F