Binary data formats have a name followed by any optional attributes. The attributes control variations within a basic format. Attributes that are recognized by specific formats are described in the usp and segy sections.

DDS automatically detects the 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. Some of these attributes are axis specific.

Padding Dead Traces: "dense.axis" causes dead traces to be padded into the correct locations for that "axis" based on the "sort.axis" Trace Header (See Axis Definitions). So normally the sort Trace Header should be set to values starting at "base.axis" (normally one) and incrementing by "step.axis" until the associated axis reaches it's "size.axis". However, if "grid.axis" is defined, then it will expect the "sort" header to start at the first "grid" value and increment to each successive "grid" value. If a Trace Header value extends beyond the "grid" values then it will linearly extrapolate based on the first two or last two "grid" values. For this purpose, the "grid" values must be monotonically increasing or decreasing.

NOTE: When padding traces on an axis, all lower axes (other than axis 1 which can never be padded this way) must also be flagged with "dense.axis". For example if "axis= t h x y" and you want to pad dead traces onto the "x" axis then you must use something like:

out_format= asp dense.h dense.x

The follow table lists the format attributes:

Attributes          Description
-----------------   -------------------------------------------
integer n           sample type and precision
float n ieee        sample type and precision
float n ieeex       sample type and precision
float n ibm         sample type and precision
complex n ieee      sample type and precision
complex n ibm       sample type and precision
hdrswap             binary and trace header "Little Endian"
                    (only for segy, segy1 and su formats)
ebcdic              segy card header
ascii               segy card header
zip [n]             zip compression with optional level 1-9 (default 6)
                    (only for generic DDS formats; not segy or usp)
green_prefix prec   "green word"† prefix & precision
green_suffix prec   "green word"† suffix & precision
no_green_prefix     no "green word"† prefix
no_green_suffix     no "green word"† suffix
slice.axis          multiple files across the given axis
sync.axis           given axis is flagged as synchronized
dense.axis          given axis is flagged as dense (non-sparse)
block               set the tape to blocked

    where "axis" is either an axis name or axis number.

Example format Definitions with explicit attributes:

comment= standard SEGY tape format
format= segy

comment= same thing, explicitly
format= segy ebcdic float 4 ibm

comment= override Samples to be ieee
format= segy float 4 ieee

comment= x-axis is to be padded out with dead traces
format= segy dense.x

comment= Same thing assuming default axis=t x y
format= segy dense.2
    

^† "Green Words" are used at times to indicate the number of bytes in a record for "usp" and "segy" formats. Many of these formats are derivatives of tape formats which have physical record marks and writing them to disk loses the record marks. So "Green Words" are ways of checking that the data is synchronized correctly with the traces. Now days, usp datasets have only a 4 byte "green word" prefix and segy datasets typically do not use them at all.