EE / circuit-design question

Hi Freelancers, I am not an EE, nor do I design circuits for a living. However, my employer has me working on a project that involves the use of an off-the-shelf circuit board. Essentially, the board is a relay controller. The question I have relates to the use of two diodes on this circuit board. On the schematic, they are labeled D? and D?, but I have circled them in red. You can see it here: [login to view URL] If you need further reference, the entire circuit is here: [login to view URL] What is the purpose of these two diodes? Why are they in the circuit? $50 to the first bidder who gives me an answer that my anal EE-wannabe boss will accept.