Fixed Width Fields

Fixed width fields are a data storage technique where every piece of data occupies a pre-determined, unchanging number of bytes. In market data feeds, this is used to ensure that the position of every field is always known, allowing for extremely fast parsing.

Because the system does not need to search for delimiters or separators, it can read data directly from memory offsets. This is essential for the low-latency requirements of options and derivatives markets.

While this approach is less flexible than variable-length formats, the performance gains in speed and predictability are unmatched. It ensures that the order book is updated with the absolute minimum delay.