@Override
	public final boolean isExternal() {
		return address.isExternalAddress();
	}
Constructs a new MemorySymbol which corresponds to the specified symbol key and has
no record.  This is intended to support dynamic label cases which do not have a record
and do not support an external address.
@param mgr the symbol manager
@param cache symbol object cache
@param addr the address associated with the symbol
@param key this must be the absolute encoding of addr
Ghidra/Framework/SoftwareModeling/src/main/java/ghidra/program/database/symbol/MemorySymbol.java