The structure of traces can be described, similar to Line Headers in the previous subsection. This allows standard and generic trace formats to be specified with the same DDS notation. Seamless Seismic Data Access is facilitated by this common framework.

All fields in a trace are created equal; DDS does not discriminate between headers and Samples. Traces may contains many fields, or only one. The seismic Samples field, if it exists, normally has the size defined by the first axis. Operations that can be applied to headers, can also be applied to Samples, and visa versa.

Fields may have any binary data type supported by DDS. Types are not limited to those supported by the host computer. The list includes character, unsigned, integer, float, and complex. Binary representations include ieee, ibm, ascii, and ebcdic. All the supported data types are described in the Data Types section.

Each field has a constant element count. If the count is greater than one, the field is a vector. If equal to one, its a scalar. If zero, no storage is reserved for a value.