A code that identifies the software component that understands this message (analogous to usb device classes or mime type strings). If this code is less than 32768, it is considered a 'registered' protocol extension and the corresponding entry should be added to https://github.com/mavlink/mavlink/extension-message-ids.xml. Software creators can register blocks of message IDs as needed (useful for GCS specific metadata, etc...). Message_types greater than 32767 are considered local experiments and should not be checked in to any widely distributed codebase.
