HDGNSS correction data consists of several different correction components. Different components are updated at different rates and also have different validity times.

Table 1 contains nominal update rates and validity periods for each correction component. The nominal update rate refers to how often new data is transmitted from the server to subscribed users. The validity period refers to how long a single correction message can still reliably be used, starting from epochTime indicated in message content. Even though the update rate may be shorter than the validity period, meaning that old data may still be valid even when new data is already available, users should start using new data as soon as it is received, as the accuracy of the old data degrades over time.

#### Table 1. Update rates and validity periods of different correction components

Correction component Nominal update rate Validity period
Orbit 5 seconds 5 minutes
Clock 5 seconds 5 minutes
Ionosphere 5 minutes 5 minutes
Code bias 24 hours 24 hours