It stands for Days Past Ovulation also know as Luteal Phase. If you know the day you ovulated, you count the next day as 1dpo, the next day as 2 dpo etc.
Here is a link to my charts. THis cycle FF has not confirmed my O date yet but look at my other charts. Anything after the red line is DPO starting with 1. They now color the boxes Orange. http://www.fertilityfriend.com/home/bec74
It stands for Days Past Ovulation also know as Luteal Phase. If you know the day you ovulated, you count the next day as 1dpo, the next day as 2 dpo etc.
Here is a link to my charts. THis cycle FF has not confirmed my O date yet but look at my other charts. Anything after the red line is DPO starting with 1. They now color the boxes Orange. http://www.fertilityfriend.com/home/bec74
Here is some articles on DPO/Luteal phase
http://www.ovulation-calculator.com/luteal-phase.htm
http://www.ovulation-calendar.com/hlp-d04-luteal-phase.html
http://www.webwomb.com/luteal_phase_frame_page.htm
I hope that helps.
~Lisa
http://www.fertilityfriend.com/home/bec74