Type descriptor
Type descriptors are used to define data types in LabVIEW. Simplest types consist of only TypeDesc ID, but more advanced ones have additional properties describing them. Compound types also contain references to the sub-types they include.
From the LabVIEW Help:
LabVIEW associates each wire and terminal on the block diagram with a data type. LabVIEW keeps track of this type with a structure in memory called a type descriptor. This type descriptor is a sequence of 32-bit integers that can describe any data type in LabVIEW. Numeric values are written in hexadecimal format, unless otherwise noted.
Note: The help text above explain how Type descriptors are stored in memory when a VI file is loaded. Their flattened form conserves space and mostly uses values smaller than 32-bit.
List of TD types
| TypeDesc ID | Description | Data Type |
|---|---|---|
| 0x00 | Void type, stores no data | Void data type |
| 0x01 | Integer with signed 1 byte (8 bit) data | I8 data type |
| 0x02 | Integer with signed 2 byte (16 bit) data | I16 data type |
| 0x03 | Integer with signed 4 byte (32 bit) data | I32 data type |
| 0x04 | Integer with signed 8 byte (64 bit) data | I64 data type |
| 0x05 | Integer with unsigned 1 byte (8 bit) data | U8 data type |
| 0x06 | Integer with unsigned 2 byte (16 bit) data | U16 data type |
| 0x07 | Integer with unsigned 4 byte (32 bit) data | U32 data type |
| 0x08 | Integer with unsigned 8 byte (64 bit) data | U64 data type |
| 0x09 | Floating point with single precision 4 byte data | Single Float data type |
| 0x0A | Floating point with double precision 8 byte data | Double Float data type |
| 0x0B | Floating point with extended (quad precision) data | Extended Float data type |
| 0x0C | Complex floating point with 8 byte data | Complex Single Float data type |
| 0x0D | Complex floating point with 16 byte data | Complex Double Float data type |
| 0x0E | Complex floating point with extended (quad precision) data | Complex Extended Float data type |
| 0x15 | Unit UInt8 | |
| 0x16 | Unit UInt16 | |
| 0x17 | Unit UInt32 | |
| 0x19 | Unit Float32 | |
| 0x1A | Unit Float64 | |
| 0x1B | Unit FloatExt | |
| 0x1C | Unit Complex64 | |
| 0x1D | Unit Complex128 | |
| 0x1E | Unit ComplexExt | |
| 0x20 | Boolean value stored on 2 bytes (16 bit), rarely used | |
| 0x21 | Boolean value stored on 1 byte (8 bit) | Boolean data type |
| 0x30 | String value | String data type |
| 0x31 | Variation of String value, probably never used | |
| 0x32 | Path value, used for disk paths, sometimes for URLs | Path data type |
| 0x33 | Picture data | Picture data type |
| 0x34 | CString | |
| 0x35 | PasString | |
| 0x37 | Tag | |
| 0x3F | SubString | |
| 0x40 | Array | |
| 0x41 | Array Data Ptr | |
| 0x4F | SubArray | |
| 0x50 | Cluster | Cluster data type |
| 0x53 | Variant data type | Variant data type |
| 0x54 | Measurement data | |
| 0x5E | Complex fixed point number | |
| 0x5F | Fixed point number | Fixed-point data type |
| 0x60 | Block | |
| 0x61 | Type block | |
| 0x62 | Void block | |
| 0x63 | Aligned block | |
| 0x64 | Repeated block, stores | |
| 0x65 | Alignment marker | |
| 0x70 | Refnum; has multiple sub-types | Reference data type |
| 0x80 | Ptr | |
| 0x83 | Ptr to | |
| 0x84 | Ext Data | |
| 0xA0 | Array interface | |
| 0xA1 | Interface to data | |
| 0xF0 | Function | |
| 0xF1 | TypeDef | |
| 0xF2 | PolyVI |