Entities
In XML, an entity is a placeholder. Entities can be placeholders for text; system entities are references to external files. Entities are most often used for three different types of information:
- Graphics
- XML fragments
- Text fragments (such as copyright statements or other often-repeated text)
When working with FrameMaker, each of these entity types is handled differently.
Graphics
FrameMaker uses an object element for referenced graphics. When you export to XML, the graphic element contains a reference to an entity name in an attribute, as shown in the following example (attributes other than entity have been truncated, as indicated by the ellipsis):
<ImportedGraphic entity = "ImportedGraphic1" .../>
At the top of the XML output file, you will find a definition for the entity:
<!ENTITY ImportedGraphic1 SYSTEM "ImportedGraphic14.gif"
NDATA gif>
This type of entity is an unparsed entity reference. The entity is unparsed because when the content is displayed as XML, the entity name is not replaced with the entity definition itself.
XML fragments
You can use entities to refer to external files that are parsed. In this case, you reference the entity in your main XML flow, as shown here:
<Book>
&ch1;
</Book>
At the top of the XML file, you will find an entity definition for ch1:
<!ENTITY ch1 SYSTEM "file01.xml">
When you export a structured book from FrameMaker to XML, the default handling is to create a system entity for each file in the book.
On import from XML, entities are not used to generate book component files. Instead, you must specify which elements will start new files in the read/write rules:
put element "Chapter" in file "ch.fm";
put element "Appendix" in file "app.fm";
put element "Glossary" in file "gloss.fm";
You can also use processing instructions to specify where to begin a new file and what file name to use.
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