Glow
The Glow DTD (Design Type Document) specification defines object types required for a device to represent its structure.
The number of types defined in Glow is limited and the most used ones are "Node" and "Parameter". A node represents a device and its elements (e.g. modules, cards, etc.). A parameter contains the properties of a control (e.g. name, read-write access, range, etc.).
Data types
To indicate the meaning and the type of the encoded data that follows next, tags are used. A tag consists of two components: a class (consisting of 1 byte) and a number (consisting of 4 bytes).
The following table provides an overview of the different classes:
| Class | Value | Description |
|---|---|---|
| Universal | 0x00 | Predefined types. Should never be used. |
| Application | 0x40 | Application-specific tags have the same meaning wherever they are seen and used. |
| Context | 0x80 | The meaning of context-specific tags depends on the location where they are seen. |
| Private | 0xD0 | A special version of the context-specific tag. |
Universal data types
| Number | Type |
|---|---|
| 1 | Boolean |
| 2 | Integer |
| 3 | Bitstring |
| 4 | Octet String |
| 5 | Null |
| 6 | Object Identifier |
| 7 | Object Descriptor |
| 8 | External |
| 9 | Real |
| 10 | Enumerated |
| 11 | Embedded Pdv |
| 12 | UTF8 String |
| 13 | Relative Object |
| 16 | Sequence |
| 17 | Set |
| 18 | Numeric String |
| 19 | Printable String |
| 20 | Teletex String |
| 21 | Videotex String |
| 22 | IA5 String |
| 23 | UTC Time |
| 24 | Generalized Time |
| 25 | Graphic String |
| 26 | Visible String |
| 27 | General String |
| 28 | Universal String |
| 29 | Unspecified String |
| 30 | BMP String |
| 31 | Last Universal |
| 0x80000000 | Application defined type |
Application data types
| Number | Type |
|---|---|
| 0 | Root |
| 1 | Parameter |
| 2 | Command |
| 3 | Node |
| 4 | ElementCollection |
| 5 | StreamCollection |
| 6 | StreamEntry |
| 7 | StringIntegerPair |
| 8 | StringIntegerCollection |
| 9 | QualifiedParameter |
| 10 | QualifiedNode |
| 11 | RootElementCollection |
The Glow specification uses a set of attributes that are used to describe a node or parameter. Refer to the Ember+ specification for more information.
Commands
| Number | Command |
|---|---|
| 30 | Subscribe |
| 31 | Unsubscribe |
| 32 | GetDirectory |