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The Querystring Environment Variable

When a process is running on the client machine, there's an environment variable known as Querystring that's part of the normal communication between the client and server machines. It contains a character string and can be assigned explicit values in your code.

Although it's based on named fields and the values assigned to those fields, it's a very dynamic entity because the names of the fields can be altered at any time. Consider the lines of code that appeared in the Searchdata.html file in the previous hour, as shown in Listing 22.1.

Listing 22.1 Explicitly Building the Querystring Parameter

1: informationstring="<A href='AdditionalInformation.asp? isbn="+isbn+"'>Click here to view additional information ...