#EMBED_DOCUMENT is a tag that is used to embed the document into the generated page rather than just referencing it. This tag has since been deprecated, being as it is a particular case of using models (see Using models) which enable the such embedding to be modularised in a more flexible and more efficient manner.
This tag can be supplemented with parameters specific to the formats employed, e.g.
[(#EMBED_DOCUMENT|autostart=true)]
Nowadays it is a much more preferred option to use its more modern interpretation when it is translated to the new functionality :
[(#MODELE{emb, autostart=true})]