DDS supports the SEG (Society of Exploration Geophysicists) SEG-Y format as "segy". The effective default attributes for segy output is:

format= segy float 4 ibm ebcdic no_green_prefix no_green_suffix

Examples of attributes available for segy (see Attributes) include the following:

Attributes            Description
---------------       ---------------------------------
no_green_prefix       no green word prefix
no_green_suffix       no green word suffix
green_prefix 4|8      green word prefix size
green_suffix 4|8      green word suffix size
integer 1|2|4|8       integer samples size
float 4|8 ibm|ieee[x] float samples type & size
hdrswap               binary and trace headers "Little Endian"
ascii                 card header text is ascii format
ebcdic                card header text is ebcdic format
charisma              charisma format
TrcNumSmp             handle variable trace lengths

Other effective segy defaults include:

axis= t x y
sort.x=CdpTrcNum
sort.y=FieldRecNum

DDS automatically detects the segy format and attributes of input binary data. If they conflict with attributes explicitly defined by format, a warning is issued and the override is honored. Output data attributes take predefined defaults, unless explicitly overridden.

The segy seismic format is described by three major types, SEGY_CARD (PREAMBLE), SEGY_BINARY (PREAMBLE2), and SEGY_TRACE (SEQUENCE). This format is created using the "${DDSROOT}/segy.fmt.dds" Dictionary. "${DDSROOT}/segy.map.dds" provides default mapping Definitions. Either of these can be copied into some other directory and edited to modify the format. Point DDS to this directory with DDS_PATH.