During the validation process, data are examined and can be flagged. For instance, data can be assigned certain attributes to describe their quality. This information can be documented and included into the database. Data are then associated to codes allowing users to further understand the data and their relevance.
As an example, UNESCO (2010) has defined a series of quality flags for water temperature and salinity data (Global Temperature-Salinity Profile Program – GTSPP) 1. In this case, quality codes are integers between 0 and 9.
|0||No quality control has been assigned to this element|
|1||The element appears to be correct|
|2||The element appears to be probably good|
|3||The element appears doubtful|
|4||The element appears erroneous|
|5||The element has been changed|
|6 to 8||Reserved for future use|
|9||The element is missing|
Units associated with each variable should be clearly noted. As an example, the Oceanographic Data Management System references section on the SLGO portal provides a description of units used for a wide range of environmental variables from athmospheric pressure to dissolved oxygen concentration. 2