Cambridge, MA - What are these signs?

[u/Wumaduce]

What do the circled signs mean? I know FDC is the fire department connection. The sign under that is max pump in pressure.

Someone said it means you guys aren't supposed to enter the building to fight a fire. If that's the case, doesn't it completely defeat the purpose of the FDC and standpipe being live?

[u/MrWhiteDelight]

That means this structure belongs to Earl Simmons