void writeExternal(DataOutput out) throws IOException {
final int offsetSecs = totalSeconds;
int offsetByte = offsetSecs % 900 == 0 ? offsetSecs / 900 : 127; // compress to -72 to +72
out.writeByte(offsetByte);
if (offsetByte == 127) {
out.writeInt(offsetSecs);
}
}
@Override
void write(DataOutput out) throws IOException {
out.writeByte(Ser.ZONE_OFFSET_TYPE);
writeExternal(out);
}