The script endep.script makes sure that where you are running the code there exists a subdirectory data.new. The output of endep is a collection of files yo??c??i010s??? and yo??c??i011s??? in the data.new directory. The file naming convention is as usual in ENDL. That is, yo identifies the emitted particle, c specifies the type of the reaction, the i number is 10 for average energy to secondary particles and 11 for average energy to the residual nucleus, and s indicates the identity of some of the numbers in the file header. The script makes a .index file for the data.new directory and then runs endlret to concatenate them into a lib.new file.