Hello Nicholas
The exit status variable is used to represent either a successful exit or a failed exit from the applet. An exit status of 0 represents a successful exit status. A non-zero value like “1” represents a failed exit status.
Exit status values can range from 0 to 255. Typically, the values of the exit status will be either 0 or 1 to represent success or failure. However, values 2-255 can be used to specify specific reasons for a failure. By default these are not used, but you can configure them for more complex EEM scripts to issue a different exit value depending upon why the script failed.
For more info, take a look at this Cisco command reference:
https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/eem/command/eem-cr-book/eem-cr-s1.html#wp3231425051
I hope this has been helpful!
Laz