240: Value missing in metadata declaration

You started a line with a squirrel @ which marks the start of a metadata declaration. But the metadata name was neither followed by a colon : to separate it from an assigned value nor by an embedded file as value.

Solution

Do not forget the colon when declaring metadata with a textual value or link:

% assign a textual value
@ author: Martin

% assign a link
@ up: ->/error/

Some metadata names can also be declared with an embedded file as value. Do not forget that all lines of embedded files in metadata declarations start with both squirrel @ and vertical bar | like this:

@ script
@|function time() {
@|    document.title = new Date().toLocaleTimeString();
@|    setTimeout(time, 5000);
@|}
@|time();

If you did not mean to declare metadata but want to use already declared metadata at the start of a line, you can wrap it in backticks so that the @ is not the line’s first character anymore:

% declare the page author
@ author: Martin

% use the @author metadata as the first word in a line
`@author` wrote this on Wednesday.

If you did not mean to do anything metadata related and just want to use a literal @ at the start of a line, you can prepend a backslash:

\@ is known as "commercial at" in Unicode.