Line Basics 1

A LINE is the basic drawing ENTITY known as a VECTOR, defined by 2 or more POINTS.
Drawing a line is easily done by using the Hotkey 'V' (vector) or click and then setting points on the drawing screen with left mouse clicks.
Enabling 'Drawing data' in 'OPTIONS->View' allows you to see both the length and the X-Y relationship of the current point to the previous point, in essence the 'box' containing the points.

Continuing to set points gives you the Overall length of the line, the size of the 'box' containing the points, and the Current length of the segment and 'box' of the last 2 points.
The PRECISION for this drawing is set at 1, which means it only figures fractions that can be expressed with one decimal place or fractions of only 1/2. This can be misleading and not a good way to get precision drawings.

Here dimensions are added with a precision of 5 decimal places to show both fractional and decimal lengths.
Drawing freehand gives you a way to sketch an idea, but not create good working drawings.

So how do we get the precision we want? We use actual length values in a selection of 'input dialogs'.
This is the Point Absolute dialog accessed with the Hotkey ':' (Colon, use SHIFT+:)

Point Absolute is the ANCHOR or ZERO POINT of your drawing and gives coordinate values to all other points in your drawing.
Point Absolute can be the corner of a plot of land, or a wall, or a machine part. Or it can be a CENTER POINT for your drawing. You decide what is best.
All points above and to the right of the ZERO (0,0) point are POSITIVE VALUES. All below and to the left are NEGATIVE values.

To relate this to a LINE we'll hit Hotkey 'V' to start the line command and then Hotkey ':' to set a point. The Point Absolute dialog by default is X=0 and Y=0. Just Hit ENTER to accept the default values and set the point.
Notice the rulers show 0,0

Hit Hotkey ':' again and enter 10 in the X input field and 10 in the Y input field. Hit ENTER.

Hit Hotkey ':' again and leave X=0 and enter 10 in the Y input field. Hit ENTER.

Click on POINTS MODE and then select the Line to show the points.
This Line has 5 points, each segment has a start and an ending point, that also starts the next segment.
Since this Line was drawn in one continuous operation it is connected together as a POLYLINE.

The INFO BOX will give you information on the box and allow you to edit the size, color, layer and other properties.
Choosing a different layer moves the object there.
Color is changed by clicking on the color icon to the left of the Same As hand.
Notice the Point: is set for 4 of 5 and above that it shows the Absolute Coordinates for that point as 0,4. You can edit that point by changing the values in the X-Y fields.
The Length value is the total length of the line, curve, arc or such. Changing the Length value adjusts the size of the object. IE: changing the value to 8 would double the size of the box.
The Bounding Box is what the objects 'envelope' is. A box fits the 'envelope' to the corners, whereas a circle or other shape is contained within an imaginary square or rectangle.
Adjusting the Bounding Box changes the size of the object to fit the new envelope.

To break a POLYLINE into individual segments, just select it and then use Edit->Selection Edit->Break Line, or Hotkey '|' ('Pipe', on the backslash key, SHIFT+\ ).
Now each segment is free and there are only a starting and ending point for each segment.

The Info Box now shows just the 2 point line segment, which can be edited by changing the values for Point Coordinates, Length, or Bounding Box.