What is ‘<<’ in AutoCAD Angle Inputs? A Forgotten Tip from the Past

<?xml encoding=”UTF-8″>By Madhukar Moogala

We have received a query from an A D N partner about usage of << in acedCommand

    
acedCommand (RTSTR, ACRX_T ("_.UCS"),
RTSTR, ACRX_T ("_Z"),
RTSTR, ACRX_T ("<<90d"),
0);

This post attempts to explain this mysterious quirk from the past!

The double left angle brackets denote clockwise or counterclockwise rotation when you rotate an entity. They make
an important role when you set the angle measurement units to DMS (Degree, Minute, Second).

When the direction of the angle is set to South, 6 o’clock:

“<<” will override to North, 12 o’clock.

Direction for angle 0°0’0″:

• East (3 o’clock) = 0°0’0″
• North (12 o’clock) = 90°0’0″
• West (9 o’clock) = 180°0’0″
• South (6 o’clock) = 270°0’0″

Let’s see an example:

First, let’s set up the AutoCAD units system to measure angles in DMS and set South to 6 o’clock.

(command "_units" "" "" "2" "" "270" "_Y")

Draw a line. // NOTE: The magenta circle is for reference.

(setq StartPt '(2 2 0))
(setq EndPt '(10 2 0))
(command "_line" StartPt EndPt "")

First Rotate with “<90”

    
(command "_rotate" (entlast) "" StartPt "<90")

Undo, and Rotate with <<90

<code>(command "_rotate" (entlast) "" StartPt "<<90")</code>