Is this a report parm - trying to convert a report I didn't write

[SBendBuckeye]

I have been asked to convert a report with the following in the SQL. What does the @ represent. I can't find any information on this anywhere. It comes up like it is expecting a query parm or something. Am I missing something obvious here?

WHERE tm.Assignment_No=[@Assignment No] And
p.Start_Date >=[@Start_Date] And

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