/ 'SRC' 0 0 6171 / (source depth 200 km: name,X1,X2,X3) / ------------------------------------------------------------------------ In this example, the source (initial point of rays) is situated in the depth of 200 km in the 5-th layer. To change the source depth to D, the middle line of the above data should be changed to: 'SRC' 0 0 6371-D / When the source depth is changed, the data set 'prem-cod.dat' must be modified in accordance with the layer (complex block) in which the source is situated: If the source is situated in the L-th layer, all codes of elementary waves in the data file 'prem-cod.dat' should begin in the L-th layer instead of the 5-th one. Note that the code of the Upgoing waves begin with double the index L if the compound-element block code (type 3) is used. ========================================================================