Firstly, the whole point about SYSEX is that the commands are, or can be, peculiar to each device, so you cannot be certain about the format except as that format may be defined for each specific device. This could well still apply between devices of the same manufacturer, but more so between different manufacturers.

There are however some generat rules which might be generally applicable. Some commands may not have the mfg items, and may immed have a command byte and data. Any like this may applicable to all manufacturers, I have a Korg NS5R manual here which has a Master Volume setting of this type.

Some other commands may have a function number, maybe followed by address values (multiple bytes, possibly being LSB and MSB) then followed by multiple (?) bytes of data. The example you give seems a little strange as if it IS LSB and MSB that there should be data following, maybe more likely it's the 4e might be a precific commads, and the next two bytes are the data to be applied. Depends what you manual says.

Regarding your specific query, there may NOT be a way to make a specific device insensitive to incoming data, However, if your device can set the channels that it will receive (respond to) you might be able to change this setting so that it will not respond to ANY channel?

Geoff