Sometimes you may wish to adjust a URL that WebCopy has detected when crawling a page, before the URL is further processed. For example, you might want to convert simple JavaScript navigation links into a URL, or remove a middle-man redirection page.
If your expression includes any of the ^, [, ., $, {, *, (, \, +, ), |, ?, <, > characters and you want them to processed as plain text, you need to "escape" the character by preceding it with a backslash. For example, if your expression was application/epub+zip this would need to be written as application/epub\+zip otherwise the + character would have a special meaning and no matches would be made. Similarly, if the expression was example.com, this should be written as example\.com, as . means "any character" which could lead to unexpected matches.