In The Matrix Revolutions (2003), using a blueprint, Roland shows a plan to defeat the Machines that are attempting to enter Zion:
Roland: The machines have taken Junction 21. The way I see it, if we drop down from broadcast here...intersect 153, we might surprise them. We'll go first, hammer as deep as we can, then blow our EMP.
What does "broadcast" mean here?
'Broadcast' is a slang way of referring to 'broadcast depth' or 'broadcast level', basically the elevation at which the Zionese hoverships are able to hack into the Matrix with a pirated signal.
Morpheus: You believe it's the year 1999 when in fact it's closer to 2199. I can't tell you exactly what year it is because we honestly don't know. There's nothing I can say that will explain it for you, Neo. Come with me. See for yourself. This is my ship, the Nebuchadnezzar. It's a hovercraft. This is the main deck. This is the core where we broadcast our pirate signal and hack into the Matrix. Most of my crew you already know. This is Apoc, Switch, and Cypher.
and
Morpheus: Dozer, when you’re done, bring the ship up to broadcast depth. We’re going in. I’m taking Neo to see her.
and
Niobe: We’re gonna do what Commander Lock ordered us to do. We’ll evacuate broadcast level and return to Zion.
"Broadcast" here refers to broadcast depth. The level below the surface of the planet that the inhabitants of Zion have to reach to in order to hack into the matrix.
As explained futher in here; Why not enter the Matrix from Zion?
The section quoted is a battle plan to move down from the broadcast depth, closer to Zion into the attacking machine army and detonate the EMP.
