public static void writeHeaderWithImports( OpcodeDefinition[] imports, OutputStream os ) throws InvalidEncoding, IOException {
		writeTbbHeader(os);
		for( int i=0; i<imports.length && i<256; ++i  ) {
			if( imports[i] == null ) continue;
			if( i == 0x41 && !LoadOpcode.INSTANCE.getUrn().equals(imports[i].getUrn()) ) {
				throw new UnsupportedOperationException("Overwriting op 0x41");
			}
			writeOpImport((byte)i, imports[i].getUrn(), os);
		}
	}