In the 15-2103, DVD_0525 uses a two-byte protocol and it is for a Pioneer two-command sequence.
I think you lucked into the correct setting for Off (see John Fine's explanation here
[Link: remotecentral.com] )
The actual signal that your device needs is Pioneer (163:153) followed by Pioneer (175:186) for Off and Pioneer (163:153) followed by Pioneer (175:187) for On.
Pioneer is NEC2 at a 40KHz carrier frequency and decodes as that with the older version of ccf2efc.
If you really want these commands, you will need to do this with a JP1 cable and that will allow you to do two byte key moves. However, the 2103 takes a fair amount of electronics expertise to just install a JP1 connection.
The better solution right now is to buy the RS 15-2104 that is being discontinued for $10 at Radio Shack stores and buy or build the cable.
If you saved your Off command in your MX you could do the following macro for discrete On: Off | Power Toggle. Also it is very likely that your unit will turn On from Off with the Play command. If So Play | Stop is your discrete On.
If you are still doing a lot of searching for discrete commands and want to get the exact commands, I highly recommend getting the 15-2104 and go the JP1 route since it will allow you to create just about any IR command out there and at a very reasonable price. If you are not going the JP1 route then the 2104 offers little more than what you have.
-Jon