The trailer1 staement is a creating the message that is needed to send the notification to your terminal.
Trailer1 is creating the following text
SE 'THE TOTAL NUMBER OF RECORDS IN FILE ARE :
and add the COUNT which shows the count of data records as 8 digits with leading zeros suppressed. And finally
Thus resulting in a single line like this
SE 'THE TOTAL NUMBER OF RECORDS IN FILE ARE : 341' U(userid)
If you're not familiar with DFSORT and DFSORT's ICETOOL, I'd suggest reading through "z/OS DFSORT: Getting Started". It's an excellent tutorial, with lots of examples, that will show you how to use DFSORT, DFSORT's ICETOOL and DFSORT Symbols. You can access it online, along with all of the other DFSORT books, from:http://www.ibm.com/servers/storage/supp ... tmpub.html