From BlenderWiki
Below is my initial attempt to translate the ProCAD GUI and documentation. A lot of work is still ahead.
Note
This is not an official document or a direct translation from Italian. It's more of a personal documentation of the script. It might contain errors.

Hopefully, this will develop into a series of pages, including a manual, translations, tutorials etcetera. Why not a CAD Mode in Blender?
Feel invited!
/Mats
 Related links
Main script window
This table is supposed to be a list with brief descriptions for quick reference. Some cleanup and reordering needed.
I've been using Blender 2.48a ProCAD 2.5 while investigating the script. The documentation I've managed to find is for Blender 2.42 ProCAD 2.2. I have been unable to run ProCAD 2.6 under any version of Blender.
Azione  Action  Description 

DCS  (Direction CursorSelection)  
DCC  (Direction CursorCursor)  Move 3D cursor the given distance in the direction given by the last stored cursor position and the current cursor position. 
DSS  (Direction SelectionSelection)  Move the 3D cursor the given distance between two selected vertices and add a vertex at the location. A dialogue follows asking for a length for an optional perpendicular line.

UC  (Undo Cursor)  Removes stored 3D cursor coordinates 
RC  (Redo Cursor)  Restores removed 3D cursor coordinates 
OG  (Object Mode) Create a new object containing a single vertex and enter edit mode.  
OC  (Object Mode) As above, but opens a dialogue for coordinates. Places the vertex in the coordinates of the active viewport, but relocates the 3D cursor to given global coordinates. This allows to easily relate the vertex created to both the active view and to global coordinates. Using Blender's native snap tools or the VER command, the vertex can quickly be snapped to the 3D cursor.  
VER  (Edit Mode) Creates a vertex at the 3D cursor (global coordinates.)  
CPA  CirclePolygonArc  Create polygons 
ELL  Ellipse  Create an ellipse 
FIG  
POL  Polyline  
PAR  Parallel  Create a parallel line 
SMU  Smooth ("Smussa")  Bevel a corner 
RAC  Join ("Raccorda")  Extends lines to their common intersection 
CO  
SPI  Edge ("Spigolo")  Add two perpendicular lines 
TAG  
SPE  
PRO  
MIS  
CCS  Center CursorSelection  Place the cursor between the current selection and the 3D cursor 
CCC  Center CursorCursor  Place 3D cursor between its current location and a location stored in memory 
CSS  Center SelectionSelection  Place 3D cursor between two selected vertices and add a vertex 
MS  Memory Selection  Add currently selected vertex coordinates to memory 
MC  Memory Cursor  Add current 3D cursor coordinates to memory 
XYZ  Move cursor a specified distance  
ORT  
DIM  
123  
X, Y, Z  
/2  
</>  
C/S  
VDI  
S>C  Snap Selection to Cursor  Move current selection to 3D cursor 
V3D  
REMDB  Remove doubles  Automatically removes double vertices 
<0.001>  Threshold for REMDB  
DEC: 3  Decimals for rounding  
PROCAD  List of hotkeys  
BLENDER  List of hotkeys  
CARICA  
ESCI  Exit script 
CPA  CirclePolygonArc
CPA (CirclePolygonArc, "CerchiPoligoniArco")  Create circles, polygons, and arcs inscribed or circumscribed into/onto a circumference. (Edit Mode)
Takes a single vertex as its initial input (use SKEY in script window) and a series of other vertices. Ouput is generated in the coordinates of the active 3D view.
For most options only the principal data are necessary. The other fields can be applied to all figures created.
Dati principali  Main data 

Num.spicchi  Number of segments (of polygon) 
Raggio  Radius (of polygon) 
Ang.iniz.  Initial angle (of arc) 
Ang.arco  (End) angle of arc 
Area  Area 
Perimetro  Perimeter 
Lato polig.  Length of polygon segments 
Comandi  Command 
Inscr/Circoscr  Inscribed/Circumscribed 
Orario/Antiorario  Clockwise/Counterclockwise 
Correzioni  Correction 
Abilita Correz.  Enable correction 
Correzione X, Y, Z  Incremental correction X, Y, Z 
Correz. Raggio  Incremental radius correction 
Dati Extra  Extra data 
Correz. R. punta  Incremental correction of center point 
Frequenza  Frequency (of center point correction) 
Input alternatives
Required input for the various available input alternatives.
Input  Required fields  Optional  

CPA  Circle passing through three points  
Three vertices  Number of segments  Arc angles, corrections  
CPA  Two points on a diameter  
Two vertices  Number of segments  Arc angles, corrections  
CPA  Two points on a radius  
Two vertices  Number of segments  Arc angles, corrections  
CPA  Center and radius  
Inital vertex  Number of segments, length of radius  Arc angles, corrections  
CPA  Center and diameter  
Initial vertex  Number of segments, length of diameter  Arc angles  
CPA  Two points and a radius  
Two vertices  Number of segments, length of radius  Arc angles, corrections  
CPA  Two extreme arc points and a radius  
Two vertices  Number of segments, length of radius  Arc angles, corrections  
Note: Circles cannot be created with this command. Because two arcs can be created out of a pair of points, proper selection of primary and secondary vertices is essential (use SKEY in script window).  
CPA  Center 3D cursor and initial selection  
Two vertices and position of 3D cursor  Number of segments  Arc angles, corrections  
Note: Proper selection of primary and seconday vertices is essential (use SKEY in script window). Use SKEY to position the 3D cursor.  
_PA  Center 3D cursor, initial selection, final (end of arc)  
Two vertices and position of 3D cursor  Number of segments  Arc angles, corrections  
Note: Circles cannot be created with this command. Proper selection of primary and secondary vertices is essential.  
CPA  Center and area  
A vertex  Number of segments, area  Arc angles, corrections  
CPA  Center and perimeter  
A vertex  Number of segments, perimeter  Arc angles, corrections  
Note: The perimeter is applied to the figure actually created, so setting arc angle to 360 degrees or 180 degrees results in different output.  
_PA  Center and polygon segment  
A vertex (for center)  Number of segments, length of polygon segments  Arc angles, corrections 
MIS  Measurements
 MIS (Misurazioni, Measurements)  Returns various measurements.
 Valid input is either
 Two 3D cursor points in memory and a vertex at current location of 3D cursor
 Position the 3D cursor on point 1, press MC.
 Position the 3D cursor on point 2, press MC.
 Position the 3D cursor on a vertex, press MIS.
 Two selected vertices and a vertex at current location of 3D cursor
 A selected line
 Two 3D cursor points in memory and a vertex at current location of 3D cursor
 Valid input is either
Console output example:  

 
MISURAZIONI  Measurements 
2 Punti come MEM CUR e vertice in cursore 3D  2 points in memory and vertex at 3D cursor 
2 punti selezionati e vertice in cursore 3D  2 selected points and vertex at 3D cursor 
Linee selezionate  Selected line 
Decimali di arrotondamento  Decimals for rounding 
Dati 3D Calcolati  Calculated 3D Data 
DP1V, DP2V, DP1P2  Distances between vertices 
AV, AP1, AP2  Hexadecimale angles at vertices 
DP1V, DP2V, DP1DP2  Distances on XY plane 
XYZ1, XYZ2. XYZV  Coordinates 
ELL  Ellipse
 ELL (ELLISSI, Ellipse)  Create an ellipse.
ELLISSI  ARCHI DI ELLISE  Ellipses  Arcs of ellipses 

Dati Principali  Main Data 
Num.spicchi  Number of segments 
Raggio asse X, Y  Radius of X, Y axes 
Ang.iniz.  Initial angle 
Ang.arco  Angle of arc 
Correzioni  Corrections 
Abilita Correz.  Enable Corrections 
Correzione Z  Z correction 
Comandi  Command 
Orario/Antiorario  Clockwise/Countercklockwise 
POL  Polar polyline
 POL  (Edit Mode) Creates a line. Opens a dialogue for polar coordinates relative to the current view and the selected vertex. Automatically selects the created vertex. (Lunghezza=Length, Angolo piano=Planar angle, Angolo incl.=Angle of inclination.) Angles clockwise from Y axis (up in view coordinates). NOTE: An angle of inclination of 90 or 90 degrees will create an endless line unless Lunghezza 3D is enabled.
 The "Lunghezza XY/3D" button determines if Length is based on Global coordinates (real length of line = Length) or viewport coordinates (appearent length of line in viewport = Length (off, default)).
 "Angolo relativo" determines if the angles are based on 3D space coordinates (default up in the 3D viewport) or coordinates stored in memory (i.e. in the direction of the stored coordinates).
PAR  Parallel lines
 PAR (Parallela, "Parallel", PKEY)  Create parallel lines. Edit Mode, Vertex and Edge Selection Mode only.
 A dialogue asks for two inputs: Distance ("Distanza") between the lines and Correction Z ("Correzione Z"), a Z offset.
 Parallel lines are added in the direction of the 3D cursor, so Distance must always be positive. Valid input include two nonconnected vertices.
 Parallel Multiple (OR Key)  ???
 Execute PAR on several lines. Output is different in edge and vertex selection modes.
SMU  Bevel, smooth
 SMU (Smussa, "Smooth")  Bevel an angle between two connected lines.
 Select the first line and click MS to add it to memory. Then select the other line and click SMU to create the bevel. A dialogue opens asking for a number of vertices ("Num.spicchi") and a radius ("Raggio").
 The lines must be coplanar to ensure there is a common vertex.
RAC  Join, extend
 RAC (Raccorda, "Join")  Extend two lines to a common intersection.
 If the extension of one line intersects the other line or the extensions of both lines intersect, two lines will be added stretching from that intersection to the nearest two endpoints of the original lines. For noncoplanar lines the appearent intersection in the current view will be created. Arbitrary results is produced for odd input (i.e. intersecting and overlapping lines) with a preference for shortest distance for the extensions returned.
 The 3D cursor is relocated to the newly added intersection but the two original lines remain selected.
CO
 CO 
SPI  Edge
 SPI  (Spigolo, "Edge") Add two cardinal lines separated by a 90 degrees angle between two vertices. (View coordinates). The 3D cursor is relocated to the newly added vertex.
TAG
 TAG 
SPE
 SPE 
PRO  Project
 PRO (Project, "Proietta")  Project vertices.
 Projects current vertex selection onto cardinal planes (i.e. XY, XZ, and YZ planes). Created vertices are separate objects included into the current selection set in Object Mode. Vertices are projected relative to the position of the 3D cursor
CCS  Center CursorSelection
 CCS  (Center CursorSelection) Center cursor between current 3D cursor and active vertex
CCC  Center CursorCursor
 CCC  (Center CursorCursor) Center cursor between 3D cursor and 3D cursor coordinates stored in memory (MC).
Center SelectionSelection
 CSS  (Center SelectionSelection) Center 3D cursor between two selected vertices and add vertex at this position. (Use the /2 and </> buttons on the right to pick other positions than the midposition.) A dialogue follows with the optional choice of adding a perpendicular line (2D, top view) from the location.
MS  Selection to Memory
 MS  (Memory Selection, SKEY) Adds a maximum of 20 selected vertices to memory.
MC  Cursor to Selection
 MC  (Memory Cursor) Adds a maximum of 20 3D cursor positions to memory.
XYZ  move 3D Cursor
 XYZ  Moves the 3D cursor. Dialogue opens for distance. Toggle axes on/off with the X, Y, and Z buttons on the right.
ORT
 ORT 
VDI
 VDI 
S>C
 S>C (Snap SelectionCursor)  Snap vertices of active object selection to 3D cursor.
 If excecuted with individual vertices in edit mode, all vertices of the active object are snapped to the 3D cursor. Object centers are not affected.
V3D
 V3D 
DIM
 DIM 
Right panels
 REMDOUB  Automatic removal of double vertices, toggles on/off.
 Removes doubles below threshold distance.
 <0,001>  Threshold for REMDB
 X, Y, Z 
 / 2 
 </> 
 C/S 
 DEC: 3  Decimals to use for rounding (?)
 PROCAD  List of PoCAD hotkeys
 BLENDER  Selected list of Blender hotkeys
 ESCI  (EKEY) Exits the script.