OakPDT Drawing

File Format
Name	OakPDT Drawing
Ontology	Electronic File Formats 3D and CAD/CAM Models OakPDT Drawing

Overview

OakPDT is a 2D parametric CAD system for RISC OS. On RISC OS systems, files in this format typically have a filetype of CAD ("PDT Dwg").

Format details

File Header
0	Byte	Major version number of the file format (always 1)
1	Byte	Minor version number of the format 2 corresponds to OakPDT v2.50 (17 November 1990)
2	Null-terminated string	The_Design_System or Oak_P_D_T_Drawing
20	Integer	Number of symbols (s)
24	Array	s symbol table entries
	Integer	Size of drawing definition (v)
	Array	v bytes
	Byte	Paper size
	Struct	Window definition
	Struct	Grid information
	Struct	Text information
	Struct	Dimension information
	Struct	Line style information
	Integer	Number of scalars (n)
	Array	n scalar table entries
	Struct	Error information
	Struct	Layer information
	Double	Dimension scale (only in v1.1 or later)
	Integer	Number of functions (n) (only in v1.2 or later)
	Array	n function table entries (only in v1.2 or later)
Symbol table entry
0	Byte	Data type
1	Byte	Pen colour In v1.2 or later, the symbol is deleted if the pen colour has bit 5 set, and the lower four bits are ANDed with %1111.
2	Byte	Layer number In v1.0 and v1.1, the symbol is deleted if the layer number is 16.
3	Byte	Line type
4	Integer	Address in drawing definition
8	Integer	Length in drawing definition (ignored in later versions)
Window definition
0	Double	Left X coordinate
8	Double	Bottom Y coordinate
16	Double	Right X coordinate
24	Double	Top Y coordinate
Grid information
0	Double	X spacing
8	Double	Y spacing
16	Double	X angle
24	Double	Y angle
32	Integer	Grid snap
36	Integer	Parametric grid snap
Text information
0	Double	Text width
8	Double	Text height
16	Double	Butterfly limit
24	Integer	Text precision
Dimension information
0	Double
8	Double
16	Double
24	Double
32	Integer
36	Integer
40	Integer
44	Integer
Line style information
0	Integer
4	Integer
8	Integer
12	Integer
Scalar table entry
0	Integer	The symbol number of the scalar.
4	Null-terminated string	The name of the scalar.
Error information
0	Integer
4	Null-terminated string
Layer information (v1.0 and v1.1)
0	Array	16 bytes containing the status of each layer. If bit 0 is set then the layer is on. If bit 1 is set then the layer is locked.
16	Array	16 bytes containing the default pen colour for each layer.
32	Byte	The active current layer.
33	Array	10 bytes mapping each pen colour to a 16 colour palette entry.
Layer information (v1.2)
0	Array	64 bytes containing the status of each layer. If bit 0 is set then the layer is on. If bit 1 is set then the layer is locked.
64	Array	64 bytes containing the default pen colour for each layer.
128	Byte	The active current layer.
129	Byte	The active points layer.
130	Byte	The active construction layer.
131	Array	10 bytes mapping each pen colour to a 16 colour palette entry.
Function table entry (v1.2 or later)
0	Null-terminated string	The name of the function.
	Integer	The number of parameters.
	Integer	The address of the function in the definition block.