Hi Ted, and welcome!
In the left column is a field called Vertical Spaces. If you put in a value of .25 (for example), it will add a vertical spacer to each segment in that row. A new addition in V3 is the ability to specify a species for this spacer. You'll find that drop-down box in the Project Properties column to the right of the screen. You can add this vertical spacer to each ring type.
One thing to know about open segments, though - if you have the box in the Project Properties checked for Auto open segments, the vertical spacer will show you the approximate width of the gap between segments but the field is un-editable. If you don't click the box to auto-calculate the gap between open segments, you can use the vertical spacer field to specify the gap. This is useful if you want all of the gaps in an open segment vessel to be the exact width as opposed to proportional if the box is checked.
One more thing on Vertical Spacers - if you add vertical spacers and then click the 'Ring View' to look at a top view of the current ring, you'll see that the vertical spacers have parallel sides. Usually, you add vertical spacers by taking a rectangular piece of wood and simply glue it to one edge of a segment and so this is how the software calculates and draws the Vertical Spacer.
My folks grew up in Northeast Montana in Plentywood and Antelope. Its been a long time since I've been back there, though, and I really need to make another trip one of these days.
Please post any other questions you might have and welcome to the community!
Lloyd Johnson