154: Embedded file not supported for this metadata name

Metadata declarations are marked with a squirrel @ at the start of a line and can be of different types: there is metadata with a textual value, there is metadata with a link as value. Some metadata names can also be used with an embedded file: htmlhead, script, style and custom marks starting with &.

A metadata declaration in your document was identified as using an embedded file, but that is not supported for the given metadata name.

Solution

If you meant to assign a textual value or a link in a metadata declaration, make sure not to forget the colon : between name and value, e.g.

% metadata declaration with a link as value
@ up: ->../

% metadata declaration with a textual value
@ author: Martin

% textual metadata with an empty value still uses a colon
@ lang:

If you did mean to assign an embedded file to a metadata name, make sure it is either htmlhead, script, style or a custom mark that starts with & followed by a single letter or digit:

@ &1
@ |<sup>1</sup>

@ style
@ |sup {color: red}

Consider linking a separate file or using a base64-encoded data URI with other metadata names:

% link to the license in a separate file
@ license: ->nutzungsbedingungen.txt

% link to the license as a data URI
@ license: ->data:text/plain;base64,QWxsIHJpZ2h0cyByZXNlcnZlZC4=

If you did not mean to declare metadata but want to use previously declared metadata at the beginning of a line in the text, you can wrap it in backticks so that the @ is not the first character of the line 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:

\@Twitter is Twitter's Twitter account.