End-of-Semester Adventure

You’re sitting downstairs at a table in MEL, trying to study for finals. You occasionally look up from your work to glance at the blinking outline of the Christmas tree on the red block wall. The colored lights are a welcome distraction from the equations you’ve been staring at.  
One of the times you glance at the tree, you notice that a blue bulb is blinking rapidly. As you watch, you see that it blinks in a fast pattern, pauses, blinks, and pauses repeatedly. Curious as to why a single bulb would be malfunctioning and eager for any excuse to procrastinate, you start googling Christmas light breakdowns.  You read a story about a man who was convinced his lights blinked in Morse code.  
Naturally, you look up Morse code and spend hours trying to determine whether the blinking bulb has a Morse code message.  Around 11 pm, a busy hour in MEL, you realize you might be on to something! The blinks seem to be spelling out real letters. You have decoded: “P Z L C S.”
What could that mean?
You think about things it could stand for, but the Z makes no sense. You try sounding it out. You wonder how it relates to MEL. Then your friend walks up unexpectedly.  “Are you doing a puzzle?” he asks, looking at your letters.  
At that moment, you have one of those breakthrough moments everyone in TAM 470 has wished they had while doing the homework.  
“PZL! Puzzle!” you say. “Does CS mean computer science?”
“Or puzzle case,” your friend says, very familiar with the innards of MEL. You know your friend is right even though he sort of stole your moment.
“Let’s go see it,” you say.
“Later,” your friend says. “I really need your help right now. Can you come to Grainger with me real quick? I left my stuff with my group there.”
Do you