Comments for code explanation of the block diagram can be added using the text labeling tool but they can occupy too much space. Many LabVIEW examples use an alternative of placing a marker label such as "1", "2", etc at desired locations which refer the viewer to another comment location on the block diagram where expanded corresponding text is displayed. This means though that diagram scrolling must be done to see the explanation for the comment. How about a Help Hint type of "hot" label that when hovered over pops up a short comment and when clicked on shows a more detailed comment. Similar to the front panel's Description and Tip but available at edit time and maybe not requiring a right click to see the full comment description - just a left click.