User`s guide

Locating a Vector of Y-axis Data
When an SDF file defines just one trace, the Y-axis Data record contains a single vector of Y-axis data.
However, when the file defines more than one trace, the record contains many vectors — one for each
trace. This section tells you how to locate one Y-axis vector in a block of many.
Single-Scan Files
When a file does not contain a Scan Structure record, the structure of the Y-axis data block is quite
simple: the order of vectors in the block is exactly the same as the order of Vector Header records in the
file. The vector described by Vector Header record 0 is first in the block, the one described by Vector
Header record 1 is second, and so on.
Multiple-Scan Files
When a file does contain a Scan Structure record, the structure of the Y-axis data block is somewhat more
complex:
• The block contains more than one set vectors.
• The vectors can be organized in two different ways.
A single scan puts a complete set of vectors in the Y-axis data block — one for each Vector Header
record. Each additional scan adds another set of vectors to the block.
The two types of vector organization are referred to as Scan and Depth. The scan_type field in the Scan
Structure record tells you which type of organization was used for your file. The following example
shows how Scan and Depth differ.
The example file contains two Data Header records and seven Vector Header records
(num_of_DATA_HDR_record and num_of_Vector_record in the File Header record have values of 2 and
7, respectively). Its Y-axis data block includes three scans of data (num_of_scan in the Scan Structure
record has a value of 3). The first Data Header record is linked to the first three Vector Header records
(total_rows
 total_cols = 3; first_VECTOR_recordNum = 0) and the second is linked to the last four
(total_rows
 total_cols = 4; first_VECTOR_recordNum = 3).
Standard Data Format (SDF)
B-34