More than one weaver can be active at once, so that, for example, a HTML Web site, a LaTeX book text, and a plain text news article can be generated simultaneously. Document lines are sent to all the active weavers for processing.
Some typesetting constructions are too complex or specialised to be represented in all weavers. In this case, verbatim text can be sent to a particular weaver, or sent to any active weavers obeying a specific protocol.