I have code in the $_POST section that would be disrupted if a user input a pipe (|) character. There are also issues with code injection hacks that use the PHP/JAVA, and others, control characters. So I am now using this method below to protect ALL my text input fields on All my forms.

I solved it with validating the input in Validations/ "Validation Rule" -->Alphanumeric<-- and adding exceptions of all the "safe" special characters --> ~ ! @ # $ % ^ & * ( ) _ ` - = + ? : ' " , . <-- specifically in the "Validation Extra" field.

I left out the { } ; | < > / \ that I understand are used to inject malicious code into input boxes as attack/hacks. This works great for me so far!

In the General tab "Description" I informed:
"Text to be displayed. <br>
(It is OK to use the characters:<br> ~ ! @ # $ % ^ & * ( ) _ ` - = + ? : ' " , . "

In the "Validation Message" I informed the user:
"Sorry, Some character in the input is invalid.
It is OK to use: ~ ! @ # $ % ^ & * ( ) _ ` - = + ? : ' " , .
But we can't allow: { } ; | < > / \ and others. If you need some other special character added, please submit a ticket."

Thought I would share. Love input on any characters I should NOT have allowed for these same reasons...