The atipl tag set does not require a separate document type definition; it can be used with all document types. The definitions for these tags are in Arbortext-path\lib\dtgen\atitag.cf, and the default formatting is defined in FOSI fragment located at Arbortext-path\lib\atipl-eic.fos.

When the layout::apply function is called, a .layout file is created, using the structures defined in the layout.dtd to specify the composed layout of the document. The atipl singleton tags are then inserted as pairs around the document material that corresponds to the composed output structure they describe. Although atipl tags are singletons, if a particular tag cannot be inserted, its logical mate will not be inserted either. For example, if a <atipl:startcolumn/> tag cannot be inserted, the <atipl:endcolumn/> tag will also not be allowed.

Each start and end tag has a set of generic attributes. Every start tag also has a predefined set of attributes that correspond to the declared attributes of the matching element of the layout.dtd. For more detailed information on the layout.dtd, refer to section The Layout file and document type. The exceptions to this correlation are that the oid and offset attributes are not required, and the <atipl:startfloat/> tag has page, span, and column number attributes.