(CSH basic construct) "@" query

While going through a script, i came across few syntax which I am not aware of what they exactly means.

@ cnt = 1
@ num_all = `echo $var`

What is the significance of "@" here. What is it called?

Csh builtin commands

Thankyou!

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Whats the difference between using @ and set?

"The @ statement in C shell is a pun: it's the "at-sign-ment" statement."
C shell - Wikipedia, the free encyclopedia