long getOffset(String vbtMangledName, int ordinal, int size) throws PdbException {
		Address address = addressByMangledName.get(vbtMangledName);
		if (address == null) {
			throw new PdbException(
				"Virtual Base Table does not exist for symbol: " + vbtMangledName);
		}
		return getOffset(address, ordinal, size);
	}
Returns offset for vbtable (mangled name) and ordinal
@param vbtMangledName mangled name of vbtable
@param ordinal index into table
@param size size of a vbt entry offset value
@return the offset
@throws PdbException if no address exists for mangled name
Ghidra/Features/PDB/src/main/java/ghidra/app/util/pdb/pdbapplicator/PdbVbtManager.java