Dimensions vs X Y coordinates

I want to use the Cartesian X-Y coordinates information in the lower left corner of the screen to draw entities on my project plan.

By using an image on a layer as a template on which to overlay a site plan drawing, I intend to generate a Letter size page for a DIY home improvement project that requires a permit.

Previously, I have had an architectural floor plan drawing scanned and rendered as a PDF.  With that file opened in Libre Draw, it was scaled to an A4 page, exported as a SVG that is then imported into LibreCAD onto a similarly sized page.  With the proper settings in Drawing Preferences, the measurement functions work.  This process was not arrived at in a straight forward manner.  Many hours of research were required off-and-on for this solution, so I cannot say I remember exactly how I got this to work.  For some reason the coordinate readout corresponds to the drawing's measurements.

With my current project, I am attempting to create a drawing within a portion of an image.  I have successfully set up the proper dimensions in the Drawing Preferences/Dimensions/General Scale and Length Factor windows so that the largest real world length will fit into the portion of the application form image/template.  The length measurement functions on the drawing correctly indicate the real world measurements.  I want to draw a line that represents a fence line that will be the the reference edge from which the other features will be placed in the drawing.

The thing that escapes me is when I want to use the X-Y readout at the bottom of the screen to create a line that will correspond to those real world dimensions, the two references do not agree.  I have been unable to adjust any parameter in either the Drawing Preferences or the Print Preview/Scale that will cause this to work.

Although I have already learned the software sufficiently to generate a couple of drawings, I do not consider myself to be a proficient LiberCAD user.  I rely mostly on the tools not the command line.

Can someone point me to what I have missed?

Please note: LibreCAD 2.1.2 on a Ubuntu 18.04 OS.

I am not sure what you are talking about. What do you mean with 'the X-Y readout at the bottom of the screen......, the two references do not agree'? The left X-Y readout refers to the absolute zero point, while the right X-Y readout refers to relative zero, the last used point, indicated by a small red circle with a cross within on the screen. Is this the point of your confusion?
In newer LibreCAD versions the right X-Y readout has an @ at the beginning to put things clear.

Thank you for responding to my post.
  My apologies for the confusion.
  I understand about the pair of Cartesian coordinates indicating the cursor's position from the absolute and movable reference points.
  I am trying to resolve that when I move the cursor vertically on the drawing page the Y value as read in the relative (movable) zero part of the lower portion of the screen does not track with the scaled value that the drawing represents.  However, the drawing's real world values do track correctly when revealed with the Dimension Lines tool.  Specifically, when the cursor moves 160' which is but 6" on the drawing the movable relative Y value reads 568 units.  For all the available adjustments I've tried, that 568 number does not change.
  And, would you tell me what are those units?  In LibreDraw and Gimp, there are a set of edge rulers indicating the page size that is being drawn/imaged onto.  In Gimp, the program defaults to pixels but can be adjusted to metric, British and other measurement systems.  I have looked into the LCAD documentation but have not found or might have scanned past that detail.
  I've done some more research through the forum using  "X-Y coordinate" as a visual search tag and eventually found a semi-related post that suggests drawing in full scale and then using the print scale function in the print preview window to bring the drawing to the intended paper size.  Because of my Gimp and LDraw bias, I had not considered this approach.  It seems to add perspective on the topic and also to the potential flaw of trying to draw within the finished paper size.  
  Does this explain the issue in a better way?
  So, have I failed to properly adjust a setting or is LibreCAD not designed to work the way I am trying to use it?
  Please advise.

Usually one sets units to what is better for the drawing, mm for mechanical, m for architecture, foot or inches if in USA,
then draws unscaled, a wall of 7 meters will be a line of 7 units, a side of a piece of 7 milimeters will be a line of 7 units if the units are meters and milimeters respectively.

Later comes the history of putting the drawing into paper...

HTH
Pere

If you set 'Length factor' to something other than 1 only the reading on the dimension line is manipulated but not the length in the drawing itself, thus xy coordinates differ.
I don't have the time at the moment to explain more, just a hint. You may have to take a different approach.

Hello AZPS

Have you solved the issue or have you given up? There has not been any further response by you.

Basically the proper procedure is to set up a drawing with the units and scale to be used (General scale = reciprocal value of intended scale, to set right size for text and arrows of dimensions), leave Length factor at 1.
Then import the image and measure a distance in it of which you know the real world length. Calculate the needed scaling factor and scale the image with Modify - Scale.
If I understand you right you want to use an image (scan or bitmap from pdf) of the application form as background in the drawing.
So the size of the application form multiplied by the reciprocal intended scale value (like General scale) is the known real world length. To make things easier you can add a rectangle/frame to the drawing according to the application form's size.
In Print Preview then set scale accordingly and position it on the sheet.

I don't know what the size of the application form and the expected scale is, but here is a sample drawing for letter size and scale 1/16"=1'.
arch_inch_1_192_letter.dxf