A sample syntax for it wuold be:
Name(text)(tip here|location)(default text|price|charge type);
or
Name(text)(tip here|location)(default text|cost per word after number of words|word|number of words);
Example:
Comment(text)(tip here|location)(|0.15|word|20);
Supposed the cost of the item is $10, if you put < 20 words in the box, its $10, > 20, its $10 + 0.15 per word after 20.