Send All From the Start
No matter what part of the program you're viewing, when you select this option and click the Send button RemoDNC will rewind right back to the top and start sending from the very beginning of the file.
Send All From Selected Line
When you click the Send button RemoDNC will start sending from the currently selected line.
Send Selected Line (Single Step)
When you click the Send button RemoDNC will send the currently selected line and immediately apply the ‘Pause’ button. You can repeatedly click (deselect) the Pause button to Single Step through your program.
When drip feeding long programs you might experience a tool break. When you're ready to restart DNC you wouldn't necessarily want to go right back to the start. You'd probably want to select a specific line and run DNC from that point. If you weren't sure about a specific area of your program you might want to single step through it.
During drip feeding at full speed you can hit pause and switch the mode to single step DNC - for example if you wanted to single step through an area you wanted to observe closely - and at any time switch the DNC back to full speed machining.