Character Based filtering will take Decimal value input from ASCII table (http://www.asciitable.com) to filter out specified characters on the ASCII table.

Sample Configuration using Webui:

1.   under proxy -> caching Proxy -> enable url filtering

2.   under Character Based Filtering,

Character Range From: 36

Character Range To: 36

The following request made by the client is going to be dropped: https://10.10.127.220/upload2.pl?abc=123;$c=y