if (len == 0) {
                        write(ID_STRING_EMPTY);
                        // don't cache empty strings
                        return;
                    } else if (len <= 256) {
                        write(ID_STRING_SMALL);
                        write(len);
                    } else if (len <= 65336) {
                        write(ID_STRING_MEDIUM);
                        writeShort(len);
                    } else {
                        write(ID_STRING_LARGE);
                        writeInt(len);