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 | SGL data type |
| 0x0A | Floating point with double precision 8 byte data | DBL data type |
| 0x0B | Floating point with extended (quad precision) data | EXT data type |
| 0x0C | Complex floating point with 8 byte data | CSG data type |
| 0x0D | Complex floating point with 16 byte data | CDB data type |
| 0x0E | Complex floating point with extended (quad precision) data | CXT data type |
| 0x15 | Enumerated UInt8 | Enum U8 data type |
| 0x16 | Enumerated UInt16 | Enum U16 data type |
| 0x17 | Enumerated UInt32 | Enum U32 data type |
| 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, storing several sub-TDs in a sequence | Cluster data type |
| 0x53 | Variant data type | Variant data type |
| 0x54 | Measurement (Waveform) data; has multiple sub-types | Waveform data type |
| 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 amount of repeats and one sub-TD to be repeated | |
| 0x65 | Alignment marker | |
| 0x70 | Refnum; has multiple sub-types, each with different set of properties | Reference data type |
| 0x73 | Set Collection | Set data type |
| 0x74 | Map Collection | Map data type |
| 0x80 | Ptr | |
| 0x83 | Ptr to | |
| 0x84 | Ext Data | |
| 0xA0 | Array interface | |
| 0xA1 | Interface to data | |
| 0xF0 | Function | |
| 0xF1 | TypeDef | |
| 0xF2 | PolyVI |