063 - superzip. Where does the data come from?

[RobinKohrs]

I'm really sorry for asking such a beginners question here, but I didn't know where else to ask. I was actually just wondering how in the 063-superzip-example the allzips-data can be used in the server.R-script. Especially this line confuses me a little bit:

zipdata <- allzips[sample.int(nrow(allzips), 10000),]

How is one able to access the data in this script, being that it never got loaded here and only gets loaded and filtered once in global.R?
Once again, sorry about this question, but happy to receive any pointer for help:)