In order to avoid excessive string object creation, all parsers optionally support string pooling. String pooling means that string objects use a single shared instance if they occur multiple times. If string pooling is used (default off), string objects should be treated as immutable.
The subsystem W3c also provides an importer for HTML documents and clipboard data (HtmlImporter) based on UTF-8 encoding. Note that it is not possible to import all HTML/CSS constructs exactly as they appear in a modern browser. However, the importer tries its best to handle at least those properties that have a correspondence in BlackBox. The importer does not handle imported or embedded style sheets but it does handle inline style attributes because clipboard HTML data is based excusively on inline styles.