[-firstname] - this parameter will save the input as the first name for the contact within the iService database. First Name is a standard field that has its own parameter (-firstname), but could also be saved using the -contactProperty parameter. Since every iService database has this field using the -firstname parameter can be more intuitive than using the -contactProperty parameter.
Example: Capture a user's first name
Please enter your first name. <br />
<br />
Email Address: $input -firstname -id'firstname'$
The above form body will generate the form shown below.