3.4. Resource Locators: the <url> type describes a <url-modifier> at
A URL is a pointer to a resource and is a functional notation denoted by
<url>. The syntax of a<url>is:
<url> = url( <string> <url-modifier>* )In addition to the syntax defined above, a can sometimes be written in other ways:
For legacy reasons, a
<url>can be written without quotation marks around the URL itself. This syntax is specially-parsed, and produces a<url-token>rather than a function syntactically. [CSS3SYN]Some CSS contexts, such as
@import, allow a<url>to be represented by a<string>instead. This behaves identically to writing aurl()function containing that string. Because these alternate ways of writing a<url>are not functional notations, they cannot accept any<url-modifier>s.Note: The special parsing rules for the legacy quotation mark-less
<url>syntax means that parentheses, whitespace characters, single quotes (') and double quotes (") appearing in a URL must be escaped with a backslash, e.g.url(open\(parens),url(close\)parens). Depending on the type of URL, it might also be possible to write these characters as URL-escapes (e.g.url(open%28parens)orurl(close%29parens)) as described in[URL]. (If written as a normal function containing a string, ordinary string escaping rules apply; only newlines and the character used to quote the string need to be escaped.)
at
The
url()function supports specifying additional<url-modifier>s, which change the meaning or the interpretation of the URL somehow. A<url-modifier>is either an<ident>or a function.This specification does not define any
<url-modifier>s, but other specs may do so.
See also CSS Values and Units Module Level 3 Editor’s Draft, 21 March 2016
What are example usages of
<ident>andfunctionaturl()?What are differences between
<string>,<ident>,functionaturl()?