Portal Form

Since I haven't dealt with portal forms, I'm not sure how implementing the logic makes it difficult, but maybe you could have something like this?

if(
len(local!test) > 20,
"You have exceeded the limit by " & len(local!test) - 20 & " characters.",
{}
)

I hope this helps, but if not, give me your information or possibly snapshots of your interface.

In portal forms, i have not seen any local varibles declared.
The tricky part is we can get the value using window.FormAPI.getValue("text89").id in the validation check but not in the validation message.

For portal forms you are pretty much stuck with JavaScript for validations -- below is one function I have used for limiting length in text fields.
/* After each character is typed the text length is checked. When the maximum text limit
is exceeded an alert pops up to notify the user and any extra characters are truncated.
The function will also works for text that is pasted into the field. The same function
can be used for any or all of the text fields on a form, with the exception of rich text fields.*/
// Usage: textLimit("simpleParagraph", 500); [attached to keyup Event]
function textLimit(field, maxLimit) {
var textareaValue = window.FormAPI.getValue(field).id;
if (textareaValue.length > maxLimit) { // if too long trim the field
textareaValue = textareaValue.substring(0, maxLimit);
var msg = "You have reached the maximum number of characters (" + maxLimit + ") allowed in this field.";
asi.alert(msg); // pop up a message to alert user
window.FormAPI.setValue(field, textareaValue);
}
}

Oh cool this is good to know. Thanks for giving this feedback Robins