Ok, my appologies this time. The part I have wrong is placing the line with a data point and then still be able to dinamically rotate that line until another data point is chosen.
In ACAD when you use the "Construction Line" (xline) tool you must specify horizontal angle or vertical. In any case you get a line of infinite length drawn.
So if Microstation had the ability with the place line tool to just place a line of a difined length (rather than infinite) equal on both sides of the cursor in one step that would be great. But what would make it better would be the ability to place that same line and be able to rotate that line until a second data point is specified. The place line command functions that way already except it does not have the line on both sides of the cursor. Even if the check box was specified as place from center point of line, so if you set the distance box to 20 and check that box it would attach the line to the cursor at 10 units from the end of the 20 unit line. Place a data point to anchor the center point and drag the cursor to rotate the line to whatever angl you wanted and click a second data point to finish the command.
So for the confusion, it has been a long time since I used ACAD.