Merge pull request #605 from AdguardTeam/feature/AG-37187

Description of using URL-encoding for $removeparam rules

docs/general/ad-filtering/create-own-filters.md

@@ -2398,19 +2398,23 @@ You can also use regular expressions to match query parameters and/or their valu
 
 **Escaping special characters**
 
-Do not forget to escape special characters like `,`, `/` and `$` in the regular expressions. Use `\` character for that purpose. For example, an escaped comma should look like this: `\,`.
+Special characters should be URL-encoded in a rule to correctly match the URL text.
+
+For example, to remove `?$param=true`, you should use the `$removeparam=%24param` rule.
 
 :::note
 
-Regexp-type rules target both name and value of the parameter. To minimize mistakes, it is safer to start every regexp with `/^` unless you specifically target parameter values.
+Spaces and commas should also be URL-encoded, otherwise the rule won't match the URL. However, `.`, `-`, `_`, and `~` should be used as they are, since they are not marked as reserved characters in URL encoding.
 
 :::
 
-We will try to detect and ignore unescaped `$` automatically using a simple rule of thumb — it is not an options delimiter if all three are true:
+Remember to escape special characters like `.` in the regular expressions. Use the `\` character to do this. For example, an escaped dot should look like this: `\.`.
+
+:::note
 
-1. It looks like `$/`
-1. There is another slash character `/` to the left of it
-1. There is another unescaped dollar sign `$` to the left of that slash character
+Regexp-type rules apply to both the name and value of the parameter. To minimize errors, it is safer to start each regexp with `/^`, unless you are specifically targeting parameter values.
+
+:::
 
 **Remove all query parameters**
 
@@ -2425,6 +2429,12 @@ Use `~` to apply inversion:
 - `$removeparam=~param` — removes all query parameters with the name different from `param`.
 - `$removeparam=~/regexp/` — removes all query parameters that do not match the `regexp` regular expression.
 
+:::note
+
+If `~` does not appear at the beginning of the rule, it is treated as a symbol in the text.
+
+:::
+
 **Negating `$removeparam`**
 
 This sort of rules work pretty much the same way it works with [`$csp`](#csp-modifier) and [`$redirect`](#redirect-modifier) modifiers.