The definition of a single value may come in different forms. Often a value is simply added as the value of a parameter or property.

A single value may be an HTML fragment such as a link, if the element type supports HTML. This is the case for space and document properties, but not for macro parameters or doctype properties. For space and document properties exist a text (encoded by a $ suffix) and a normalized (encoded by a § suffix) version for a property value. In case of an HTML link the text version is the label, the normalized version is the URI of the link.

Since single values may be specified as members of a list they typically must not contain a comma. Also single values are matched in queries and therefore must not contain any characters that are significant in searches.

The following characters are typically not allowed.

1. comma
2. opening an closing bracket of any kind
3. quotes or double quotes

The current version of the projectdoc Toolbox does not provide tools to escape characters. This may change in future versions so that the characters above may be allowed.