Need help to structured text

Good morning, Guys:
I have a structured text (Rslogix 5000), i couldn't understand it.
can anyone help me and explain its meaning.
thanks!

looks like a flip flop

This is the code:
To know what it does you have to know what r1_rls, as_rbr and as_lbr are.
Otherwise the code does what it says it does.

Search for "if then else" statement on the net if you don't know how it works.
It works the same in all computer languages.

Nice work Steve.
It shows how verbose structured text can become when doing logic with it.

Reminds me of a training course I went to on Steeplechase software many years ago. Steeplechase was flow charting software touted as an alternative to ladder logic. The pitch was that ladder logic required "specialized knowledge" to understand whereas flow charting was more intuitive. The first lab exercise was to do a simple start/stop seal-in circuit using a flowchart. It took a couple of pages to write it and the end result was pretty ugly. I made the mistake of pointing out that it was a clear case where ladder logic was a better tool for the application. The instructor gave me a dirty look and refused to deviate from the company line that relay ladder logic was dying as an automation programming language and that anyone still using it had better wake up to that fact before they found themselves out of a job. That was 25 years ago.
I'm not saying there is no place for structured text. There are many applications where it is a better fit. This just wasn't one of them.

this structured text is for one of steps of the initializing setup .
the program is running very well so far, since i am not the programmer who programs it. it gives me some confusion.after I read some more rest of the programs, now I understand a little better.
thanks to everyone to help me!

or
r1_rls:=(r1_rls and not as_rbr) or (r1_rls and as_lbr)

Still nowhere as readable in ladder