# What does the comma mean in m, c := E(K, m)

Disclaimer: I'm a beginner to cryptography.

Background: I'm reading Cryptography Engineering by Ferguson, Schneier, and Kohno, where the authors use this image:

Question: What do the commas mean here?

My attempt: m, c := --- seems to mean "given" m, c equals ...

It's a comma to separate the two things. Alice has $m$ and can calculate $c$ which is equal to $E(K_{e}, m)$. Bob has $c$ and can calculate $m$ which is equal to $D(K_{e}, c)$.