Mtext Line Spacing

From AutoCAD Help:

If you enter ‑mtext (precede with hyphen) at the Command prompt, MTEXT bypasses the In-Place Text Editor and displays additional prompts on the command line.
Current text style: current Text height: current
Specify first corner:
Specify opposite corner or [Height/Justify/Line spacing/Rotation/Style/Width]:

Line Spacing
Specifies line spacing for the multiline text object.
Line spacing is the vertical distance between the bottom (or baseline) of one line of text and the bottom of the next line of text.
Note Exact spacing is recommended when you use MTEXT to create a table. Use a smaller text height than the specified line spacing to ensure that text does not overlap.

Enter line spacing type [At least/Exactly] :

At Least
Adjusts lines of text automatically based on the height of the largest character in the line. When At Least is selected, lines of text with taller characters have added space between lines.
Enter line spacing factor or distance :
Spacing Factor: Sets the line spacing to a multiple of single-line spacing.
Single spacing is 1.66 times the height of the text characters. You enter the spacing increment as a number followed by x to indicate a multiple of single spacing. For example, specify single spacing by entering 1x, or specify double spacing by entering 2x.
Distance: Sets the line spacing to an absolute value measured in drawing units. Valid values must be between 0.0833 (0.25x) and 1.3333 (4x).

Exactly
Forces the line spacing to be the same for all lines of text in the multiline text object. Spacing is based on the text height of the object or text style.
Enter line spacing factor or distance :
Spacing Factor: Sets the line spacing to a multiple of single-line spacing.
Single spacing is 1.66 times the height of the text characters. You can enter a spacing factor as a number followed by x to indicate a multiple of single spacing. For example, specify single spacing by entering 1x, or specify double spacing by entering 2x.
Distance: Sets the line spacing to an absolute value measured in drawing units. Valid values must be between 0.0833 (0.25x) and 1.3333 (4x).