This data record must be input before any wave spectra. The maximum number of wave spectra is 20.

      2   5  7   11    16    21         31    36
    - --- -- ---- ----- ----- ---------- ----- -----
   |X|   |  |SPDN|     |     |          |XXXXX|     |
    - --- -- ---- ----- ----- ---------- ----- -----
       |  |   |     |     |       |              |
       |  |   |     |     |       |              |_(4) No. of Gaussian integral angles (I5)
       |  |   |     |     |       |              
       |  |   |     |     |       |_(3)Direction of Spectrum in Degrees (F10.0)
       |  |   |     |     |
       |  |   |     |     |_(2)Total Wave Spreading Angle in Degrees (I5)
       |  |   |     |
       |  |   |     |_(1)Power of Wave Spreading Function (I5)
       |  |   |
       |  |   |_Compulsory Data Record Keyword(A4)
       |  |
       |  |_Optional User Identifier(A2)
       |
       |_Compulsory END on last data record in data category(A3)

(1) This is only required for a spreading sea. This value defines the power N of the wave spreading function which is in the form of , where . If this space is blank and a spreading angle is input in (2) the power defaults to .

(2) This value defines the total spreading angle for the case when . The maximum permitted angle is 180 degrees. If this space should be left blank as the total spreading angle is set to 180 degrees.

(3) This value is the direction of waves within a wave spectrum (for a spreading sea, this is the direction in which the wave spectra values are the highest). All the following specifications of wave spectra take this value until another SPDN data record is input. The next group of wave spectra will then take the new value as the wave direction. It is therefore a mandatory requirement that this data record is the first data record of the wave spectrum data category, as the wave direction will be undefined until this data record is input.

(4) This value is the number of Gaussian integration angles to represent a spreading sea. The default value is 7 and the maximum allowed value is 28. If (4) is blank or less than the default value, is used. If (4) is greater than 28, is set to 28.

For a non-spreading sea, (1), (2), and (4) should be left blank.

The introduction of a SPDN data record thus enables the user to alter the value of the wave direction for a complete group of wave spectra.